2025 |
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| 329. | Young-Geun Kang; Seungwoon Park; Eunsung Kim; Jinuk Lee; Kyeongrok Kim; Sangtae Kim; Seong-Ook Park Ground-Moving Target Indication Using Along Track SAR Interferometer Designed with Triangular Frequency-Modulated Continuous Wave Radar Journal Article IEEE Transactions on Instrumentation and Measurement, n (n), pp. 1-1, 2025, ISSN: 1557-9662. Abstract | Links | BibTeX | 태그: International @article{Kang2025, title = {Ground-Moving Target Indication Using Along Track SAR Interferometer Designed with Triangular Frequency-Modulated Continuous Wave Radar}, author = {Young-Geun Kang and Seungwoon Park and Eunsung Kim and Jinuk Lee and Kyeongrok Kim and Sangtae Kim and Seong-Ook Park }, url = {http://ma.kaist.ac.kr/wp-content/uploads/2025/03/Ground-Moving_Target_Indication_Using_Along-Track_SAR_Interferometer_Designed_With_Triangular_Frequency-Modulated_Continuous_Wave_Radar.pdf}, doi = {10.1109/TIM.2025.3541704}, issn = {1557-9662}, year = {2025}, date = {2025-02-13}, journal = {IEEE Transactions on Instrumentation and Measurement}, volume = {n}, number = {n}, pages = {1-1}, abstract = {Synthetic aperture radar-ground-moving target indication (SAR-GMTI) system generates two-dimensional images of the observed area and detects moving targets within the image. Along track SAR interferometry (ATI) is gaining attention as a useful GMTI technique because it not only detects moving objects but also estimates the radial velocities of the detected objects. To unambiguously estimate the velocities of the moving objects with an ATI system, implementing a multi-baseline system with multi-channel is required, and frequency-modulated continuous wave (FMCW) radars are appropriate for multi-channel implementation due to their inherent bistatic properties. This paper proposes a practical and efficient SAR-GMTI design method that implements an ATI system with a triangular FMCW radar. The system is lightweight and affordable because it only requires a single FMCW radar. In addition, by adopting a triangular transmission signal model, the proposed system achieves the ability to distinguish signals for two channels in a single receiver. The usefulness of the proposed technique will be emphasized through comparison with the existing SAR-GMTI method using FMCW radars. Furthermore, the GMTI field test results using a van as a SAR platform are presented to demonstrate the validity of the proposed system. The experiment results of detecting multiple objects moving at various velocities validate the practicality of the proposed system. A method to verify the accuracy of the estimated velocities is also given.}, keywords = {International}, pubstate = {published}, tppubtype = {article} } Synthetic aperture radar-ground-moving target indication (SAR-GMTI) system generates two-dimensional images of the observed area and detects moving targets within the image. Along track SAR interferometry (ATI) is gaining attention as a useful GMTI technique because it not only detects moving objects but also estimates the radial velocities of the detected objects. To unambiguously estimate the velocities of the moving objects with an ATI system, implementing a multi-baseline system with multi-channel is required, and frequency-modulated continuous wave (FMCW) radars are appropriate for multi-channel implementation due to their inherent bistatic properties. This paper proposes a practical and efficient SAR-GMTI design method that implements an ATI system with a triangular FMCW radar. The system is lightweight and affordable because it only requires a single FMCW radar. In addition, by adopting a triangular transmission signal model, the proposed system achieves the ability to distinguish signals for two channels in a single receiver. The usefulness of the proposed technique will be emphasized through comparison with the existing SAR-GMTI method using FMCW radars. Furthermore, the GMTI field test results using a van as a SAR platform are presented to demonstrate the validity of the proposed system. The experiment results of detecting multiple objects moving at various velocities validate the practicality of the proposed system. A method to verify the accuracy of the estimated velocities is also given. |
| 328. | Youngin Yoo; Jinki Park; Changjae Lee; Dongki Yoon; Seong Ook Park Reconfigurable Multibeam Holographic Antenna Based on Liquid-Crystal Technology for Ka-Band LEO Satellite Application Journal Article IEEE Access, 13 , pp. 27141-27149, 2025, ISSN: 2169-3536. Abstract | Links | BibTeX | 태그: International @article{Yoo2025, title = {Reconfigurable Multibeam Holographic Antenna Based on Liquid-Crystal Technology for Ka-Band LEO Satellite Application}, author = {Youngin Yoo and Jinki Park and Changjae Lee and Dongki Yoon and Seong Ook Park}, url = {http://ma.kaist.ac.kr/wp-content/uploads/2025/02/Reconfigurable_Multibeam_Holographic_Antenna_Based_on_Liquid-Crystal_Technology_for_Ka-Band_LEO_Satellite_Application.pdf}, doi = {10.1109/ACCESS.2025.3538044}, issn = {2169-3536}, year = {2025}, date = {2025-02-03}, journal = {IEEE Access}, volume = {13}, pages = {27141-27149}, abstract = {The requirements of low Earth orbit (LEO) satellite systems for high-precision and selective multiple coverage, have driven much interest and demand for millimeter-wave multibeam antennas. However, the key challenge is to provide fully independent control of each beam with a single source, and metasurfaces have paved the way to solve this problem. Here, we present a reconfigurable multibeam holographic antenna (HA) at 36 GHz. In particular, we used liquid crystals (LC) to implement a low power consumption and lightweight antenna. Each unit cell is selectively driven by connected bias lines according to the calculated holographic pattern. Consequently, the proposed multibeam HA can radiate in the desired direction and control each beam independently. Furthermore, the gain difference in each beam can be corrected by the amplitude coefficient to radiate with nearly equal gain in each direction. The proposed HA demonstrated the scanning range of 60° at 36 GHz, with a peak gain of 8.7 dBi. Additionally, the peak directivity is 12.7 dBi, the 3-dB bandwidth is about 1 GHz at the center frequency of 36 GHz, and the operating bandwidth is 2.8 GHz ( 34.8−37.6 GHz).}, keywords = {International}, pubstate = {published}, tppubtype = {article} } The requirements of low Earth orbit (LEO) satellite systems for high-precision and selective multiple coverage, have driven much interest and demand for millimeter-wave multibeam antennas. However, the key challenge is to provide fully independent control of each beam with a single source, and metasurfaces have paved the way to solve this problem. Here, we present a reconfigurable multibeam holographic antenna (HA) at 36 GHz. In particular, we used liquid crystals (LC) to implement a low power consumption and lightweight antenna. Each unit cell is selectively driven by connected bias lines according to the calculated holographic pattern. Consequently, the proposed multibeam HA can radiate in the desired direction and control each beam independently. Furthermore, the gain difference in each beam can be corrected by the amplitude coefficient to radiate with nearly equal gain in each direction. The proposed HA demonstrated the scanning range of 60° at 36 GHz, with a peak gain of 8.7 dBi. Additionally, the peak directivity is 12.7 dBi, the 3-dB bandwidth is about 1 GHz at the center frequency of 36 GHz, and the operating bandwidth is 2.8 GHz ( 34.8−37.6 GHz). |
2024 |
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| 327. | Kyung-Bin Bae; Youngin Yoo; Seungwoon Park; SeongOok Park A Novel Channel Sounding Method Based on Pulsed LFM Signal for mm-Wave Application Instrumentation Measurement and Analysis Journal Article IEEE Transactions on Instrumentation and Measurement, 74 (8501216), 2024, ISSN: 1557-9662. Abstract | Links | BibTeX | 태그: International @article{Bae2024, title = {A Novel Channel Sounding Method Based on Pulsed LFM Signal for mm-Wave Application Instrumentation Measurement and Analysis}, author = {Kyung-Bin Bae and Youngin Yoo and Seungwoon Park and SeongOok Park}, url = {http://ma.kaist.ac.kr/wp-content/uploads/2025/02/A_Novel_Channel_Sounding_Method_Based_on_Pulsed_LFM_Signal_for_mm-Wave_Application_Instrumentation_Measurement_and_Analysis-1.pdf}, doi = {10.1109/TIM.2024.3522635}, issn = {1557-9662}, year = {2024}, date = {2024-12-25}, journal = {IEEE Transactions on Instrumentation and Measurement}, volume = {74}, number = {8501216}, abstract = {Recently, there has been increasing demand to exploit a wider spectrum in higher frequency bands to improve the performance of new wireless communication devices and systems for millimeter-wave (mm-Wave) communications and fifth-generation (5G) mobile networks. Channel measurement and modeling are crucial for the design and development of such 5G devices and systems. In general, among various channel sounding methods, the most appropriate method has been selectively used depending on the channel characteristics to be measured. In this article, we propose an advanced sounding technique based on linear frequency modulation (LFM) pulse signal to strengthen channel sounding capabilities fitting well in higher frequency bands. The unique property of the LFM signal, where the instant frequency change corresponds to the sweep time, ensures that the output of the proposed channel sounder is proportional to the scattering parameter. Using this, we present an extended capability of the proposed sounding technique to measure channel characteristics such as delay spread, Doppler spread (DS), and Rician-K factor of small-scale fading channels emulated in a reverberation chamber (RC).}, keywords = {International}, pubstate = {published}, tppubtype = {article} } Recently, there has been increasing demand to exploit a wider spectrum in higher frequency bands to improve the performance of new wireless communication devices and systems for millimeter-wave (mm-Wave) communications and fifth-generation (5G) mobile networks. Channel measurement and modeling are crucial for the design and development of such 5G devices and systems. In general, among various channel sounding methods, the most appropriate method has been selectively used depending on the channel characteristics to be measured. In this article, we propose an advanced sounding technique based on linear frequency modulation (LFM) pulse signal to strengthen channel sounding capabilities fitting well in higher frequency bands. The unique property of the LFM signal, where the instant frequency change corresponds to the sweep time, ensures that the output of the proposed channel sounder is proportional to the scattering parameter. Using this, we present an extended capability of the proposed sounding technique to measure channel characteristics such as delay spread, Doppler spread (DS), and Rician-K factor of small-scale fading channels emulated in a reverberation chamber (RC). |
| 326. | Jinki Park; Youngin Yoo; Changjae Lee; Dong Ki Yoon; Seong-Ook Park Liquid-Crystal-Based Beam Steering Guided-Wave Metasurface Antenna at Millimeter-Wave Band Journal Article IEEE Antennas and Wireless Propagation Letters, 2024. Abstract | Links | BibTeX | 태그: International @article{Park2024, title = {Liquid-Crystal-Based Beam Steering Guided-Wave Metasurface Antenna at Millimeter-Wave Band}, author = {Jinki Park and Youngin Yoo and Changjae Lee and Dong Ki Yoon and Seong-Ook Park}, doi = {10.1109/LAWP.2024.3439587}, year = {2024}, date = {2024-08-06}, journal = {IEEE Antennas and Wireless Propagation Letters}, abstract = {In this paper, we present the design and fabrication of a liquid crystal (LC)-based metasurface antenna for millimeter-wave beam steering applications. Unlike the conventional beamforming systems that rely on phase shifters, our approach harnesses the electrical tunability of LCs. We target a frequency of 34.5 GHz, taking advantage of the pronounced low dielectric loss characteristics exhibited by LCs. The proposed antenna uses a substrate integrated waveguides (SIW) to feed millimeter-wave to metasurface unit cells, and each cell’s radiation is controlled through DC voltage biasing of the LC. The measurement results demonstrate a beam steering range of 120° with a maximum gain of 10.754 dBi and a sidelobe level (SLL) of -11.562 dBc at the boresight.}, keywords = {International}, pubstate = {published}, tppubtype = {article} } In this paper, we present the design and fabrication of a liquid crystal (LC)-based metasurface antenna for millimeter-wave beam steering applications. Unlike the conventional beamforming systems that rely on phase shifters, our approach harnesses the electrical tunability of LCs. We target a frequency of 34.5 GHz, taking advantage of the pronounced low dielectric loss characteristics exhibited by LCs. The proposed antenna uses a substrate integrated waveguides (SIW) to feed millimeter-wave to metasurface unit cells, and each cell’s radiation is controlled through DC voltage biasing of the LC. The measurement results demonstrate a beam steering range of 120° with a maximum gain of 10.754 dBi and a sidelobe level (SLL) of -11.562 dBc at the boresight. |
| 325. | Jing Huang; Seung-Joo Jo; Chang-Won Seo; Si-A Lee; Seong-Sik Yoon; Seong-Ook Park Electrical Performance Analysis and Prediction for Complex Mesh based on Model Angles Journal Article IEEE Access, 2024. Abstract | Links | BibTeX | 태그: International @article{Huang2024, title = {Electrical Performance Analysis and Prediction for Complex Mesh based on Model Angles}, author = {Jing Huang and Seung-Joo Jo and Chang-Won Seo and Si-A Lee and Seong-Sik Yoon and Seong-Ook Park}, url = {http://ma.kaist.ac.kr/wp-content/uploads/2024/08/Electrical_Performance_Analysis_and_Prediction_for_Complex_Mesh_based_on_Model_Angles.pdf}, doi = {10.1109/ACCESS.2024.3431037}, year = {2024}, date = {2024-07-19}, journal = {IEEE Access}, abstract = {The metallic mesh serves as a reflecting surface on deployable reflector antennas for satellites. Electrical properties differ for meshes with different knitting patterns. Also, pattern shapes vary at different tensions due to the elasticity of the mesh. Furthermore, mesh models for electrical performance analysis become more challenging to construct as the mesh knitting patterns become more intricate. A method based on model angles and diagonals is developed in this paper to overcome the aforementioned problems. First, procedures for building a mesh model are described. Then three mesh models of the single Atlas mesh, the single Satin mesh, and the Max mesh are built. The corresponding performance variations are observed and stabilities are compared. Moreover, the wire diameter for the mesh model is determined by measuring the reflectance of the Max mesh and comparing it with simulation results. Afterward, correlations between the reflectivity and incident angles are presented. In addition, the reflectance and transmittance at different incidence angles are measured. Measured results align well with simulated results. It verifies the accuracy of the simulated characteristics and the value of the mesh model in understanding mesh electrical properties.}, keywords = {International}, pubstate = {published}, tppubtype = {article} } The metallic mesh serves as a reflecting surface on deployable reflector antennas for satellites. Electrical properties differ for meshes with different knitting patterns. Also, pattern shapes vary at different tensions due to the elasticity of the mesh. Furthermore, mesh models for electrical performance analysis become more challenging to construct as the mesh knitting patterns become more intricate. A method based on model angles and diagonals is developed in this paper to overcome the aforementioned problems. First, procedures for building a mesh model are described. Then three mesh models of the single Atlas mesh, the single Satin mesh, and the Max mesh are built. The corresponding performance variations are observed and stabilities are compared. Moreover, the wire diameter for the mesh model is determined by measuring the reflectance of the Max mesh and comparing it with simulation results. Afterward, correlations between the reflectivity and incident angles are presented. In addition, the reflectance and transmittance at different incidence angles are measured. Measured results align well with simulated results. It verifies the accuracy of the simulated characteristics and the value of the mesh model in understanding mesh electrical properties. |
| 324. | Han-Sol Kim; Jiyeol Meang; Ju-Hye Kim; Dong-Sik Ko; Seong-Ho Seo; Muhammad Tayyab Azim; Seong-Ook Park Miniaturized 24GHz FMCW Radar Leakage Mitigation with Synchronized Subtraction Journal Article IEEE Sensors Journal, 2024. Abstract | Links | BibTeX | 태그: International @article{Kim2024, title = {Miniaturized 24GHz FMCW Radar Leakage Mitigation with Synchronized Subtraction}, author = {Han-Sol Kim and Jiyeol Meang and Ju-Hye Kim and Dong-Sik Ko and Seong-Ho Seo and Muhammad Tayyab Azim and Seong-Ook Park}, url = {http://ma.kaist.ac.kr/wp-content/uploads/2024/08/Miniaturized_24GHz_FMCW_Radar_Leakage_Mitigation_with_Synchronized_Subtraction-압축됨.pdf}, doi = {10.1109/JSEN.2024.3422397}, year = {2024}, date = {2024-07-11}, journal = {IEEE Sensors Journal}, abstract = {Frequency-modulated continuous wave (FMCW) radar sensors are widely used to measure range, velocity, and target status. As the range of applications for FMCW radar sensors expands, there is an increasing demand for smaller FMCW radar sensors suitable for use in confined spaces. To reduce the form factor of the FMCW radar sensor, the distance between the transmit (Tx) and receive (Rx) antennas is also reduced. This decrease in antenna separation increases the magnitude of the leakage signal transmitted from the Tx to the Rx antenna. However, the leakage signal makes it difficult for the FMCW radar sensor to detect the target by increasing the noise floor. In this article, we present an advanced method to mitigate the increased leakage signal power in the miniaturized FMCW radar sensor. We have fabricated a miniaturized homodyne FMCW radar with consistent leakage signal characteristics. We also propose a method to minimize the influence of the leakage signal by storing the leakage signal characteristics and using the stored data when operating the radar. Experimental results show significant leakage signal power reduction. This technique not only preserves the power of the received target signals but also improves the overall performance of compact FMCW radar sensors. The proposed method provides a basis for miniaturized radar sensors to contribute to various industries by providing an effective solution to the leakage signal problem of small radar technology.}, keywords = {International}, pubstate = {published}, tppubtype = {article} } Frequency-modulated continuous wave (FMCW) radar sensors are widely used to measure range, velocity, and target status. As the range of applications for FMCW radar sensors expands, there is an increasing demand for smaller FMCW radar sensors suitable for use in confined spaces. To reduce the form factor of the FMCW radar sensor, the distance between the transmit (Tx) and receive (Rx) antennas is also reduced. This decrease in antenna separation increases the magnitude of the leakage signal transmitted from the Tx to the Rx antenna. However, the leakage signal makes it difficult for the FMCW radar sensor to detect the target by increasing the noise floor. In this article, we present an advanced method to mitigate the increased leakage signal power in the miniaturized FMCW radar sensor. We have fabricated a miniaturized homodyne FMCW radar with consistent leakage signal characteristics. We also propose a method to minimize the influence of the leakage signal by storing the leakage signal characteristics and using the stored data when operating the radar. Experimental results show significant leakage signal power reduction. This technique not only preserves the power of the received target signals but also improves the overall performance of compact FMCW radar sensors. The proposed method provides a basis for miniaturized radar sensors to contribute to various industries by providing an effective solution to the leakage signal problem of small radar technology. |
| 323. | Changjae Lee; Jinki Park; Ye-Eun Chi; Youngin Yoo; Seong-Ook Park; Dong Ki Yoon Ultralow-Voltage Frequency Tunning of Liquid Crystal-Based GHz Antenna via Nanoscratching Method Journal Article Advanced Materials Technologies, 9 (7), pp. 2301859, 2024. Abstract | Links | BibTeX | 태그: International @article{Lee2024, title = {Ultralow-Voltage Frequency Tunning of Liquid Crystal-Based GHz Antenna via Nanoscratching Method}, author = {Changjae Lee and Jinki Park and Ye-Eun Chi and Youngin Yoo and Seong-Ook Park and Dong Ki Yoon}, doi = {10.1002/admt.202301859}, year = {2024}, date = {2024-02-12}, journal = {Advanced Materials Technologies}, volume = {9}, number = {7}, pages = {2301859}, abstract = {Liquid crystal (LC)-based radio-frequency (RF) tunable antennas garner attention because of their compact size and minimal heat generation. Exploiting the LC's property to alter the RF permittivity depending on its alignment, voltage-induced orientational switching enables frequency modulation of the radiated wave. To ensure dependable antenna performance, precise control of the initial LC alignment is crucial, which is conventionally achieved by polyimide (PI) coating followed by the rubbing process (PI-rubbing). However, this approach demands high temperature (200 °C) and prolonged processing time (2 h), while also necessitating high voltage for LC reorientation due to induced excessive surface polar anchoring strength. Here, a PI-free-nanoscratching method creating 1D channels is introduced that induces initial LC alignment in a desired direction. The initial orienting capability of the scratched metal surface is superior to that of the PI-rubbed surface. Furthermore, the LC-based antenna employing the nanoscratching method shows a remarkable resonance frequency shift of up to 3 GHz with a low voltage of 2 V. This driving voltage is five times lower than that of antennas using the conventional PI-rubbing method, which can open a new era for the next generation LC-antenna.}, keywords = {International}, pubstate = {published}, tppubtype = {article} } Liquid crystal (LC)-based radio-frequency (RF) tunable antennas garner attention because of their compact size and minimal heat generation. Exploiting the LC's property to alter the RF permittivity depending on its alignment, voltage-induced orientational switching enables frequency modulation of the radiated wave. To ensure dependable antenna performance, precise control of the initial LC alignment is crucial, which is conventionally achieved by polyimide (PI) coating followed by the rubbing process (PI-rubbing). However, this approach demands high temperature (200 °C) and prolonged processing time (2 h), while also necessitating high voltage for LC reorientation due to induced excessive surface polar anchoring strength. Here, a PI-free-nanoscratching method creating 1D channels is introduced that induces initial LC alignment in a desired direction. The initial orienting capability of the scratched metal surface is superior to that of the PI-rubbed surface. Furthermore, the LC-based antenna employing the nanoscratching method shows a remarkable resonance frequency shift of up to 3 GHz with a low voltage of 2 V. This driving voltage is five times lower than that of antennas using the conventional PI-rubbing method, which can open a new era for the next generation LC-antenna. |
| 322. | Myoung-Ho Chae; Seong-Ook Park; Seung-Ho Choi; Chae-Taek Choi Reinforcement Learning-Based Counter Fixed-Wing Drone System Using GNSS Deception Journal Article IEEE Access, 12 , pp. 16549 - 16558, 2024. Abstract | Links | BibTeX | 태그: International @article{Chae2024, title = {Reinforcement Learning-Based Counter Fixed-Wing Drone System Using GNSS Deception}, author = {Myoung-Ho Chae and Seong-Ook Park and Seung-Ho Choi and Chae-Taek Choi}, url = {http://ma.kaist.ac.kr/wp-content/uploads/2024/08/Reinforcement_Learning-Based_Counter_Fixed-Wing_Drone_System_Using_GNSS_Deception-2-압축됨.pdf}, doi = {10.1109/ACCESS.2024.3358211}, year = {2024}, date = {2024-01-24}, journal = {IEEE Access}, volume = {12}, pages = {16549 - 16558}, abstract = {As drone intrusions into important facilities have increased, research on drone countermeasures has been conducted to counter drones. In this study, we developed a reinforcement learning (RL)-based counter fixed-wing drone system that can respond to fixed-wing drones in autonomous flight with soft kills. The system redirects fixed-wing drones to a designated target position using the global navigation satellite system (GNSS) deception based on the drone’s position and speed measured by RADAR. In this study, to construct an environment for training an RL agent, simplified drone modeling was performed for two types of fixed wing drones, and the RADAR error measured through flight tests was modeled. Subsequently, the Markov decision process (MDP) was defined to enable redirection without prior information regarding fixed-wing drones. After applying the RL agent trained in the defined MDP and environment to the counter fixed-wing drone system, the simulation and flight test results confirmed that redirection was possible for both types of fixed-wing drones.}, keywords = {International}, pubstate = {published}, tppubtype = {article} } As drone intrusions into important facilities have increased, research on drone countermeasures has been conducted to counter drones. In this study, we developed a reinforcement learning (RL)-based counter fixed-wing drone system that can respond to fixed-wing drones in autonomous flight with soft kills. The system redirects fixed-wing drones to a designated target position using the global navigation satellite system (GNSS) deception based on the drone’s position and speed measured by RADAR. In this study, to construct an environment for training an RL agent, simplified drone modeling was performed for two types of fixed wing drones, and the RADAR error measured through flight tests was modeled. Subsequently, the Markov decision process (MDP) was defined to enable redirection without prior information regarding fixed-wing drones. After applying the RL agent trained in the defined MDP and environment to the counter fixed-wing drone system, the simulation and flight test results confirmed that redirection was possible for both types of fixed-wing drones. |
2023 |
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| 321. | Young-Geun Kang; Seong-Ook Park A Full-Aperture Frequency Scaling Algorithm for Processing Dechirped Sliding Spotlight SAR Data Journal Article IEEE Access, 11 , pp. 92550-92564, 2023. Abstract | Links | BibTeX | 태그: International @article{Kang2023b, title = {A Full-Aperture Frequency Scaling Algorithm for Processing Dechirped Sliding Spotlight SAR Data}, author = {Young-Geun Kang and Seong-Ook Park}, url = {http://ma.kaist.ac.kr/wp-content/uploads/2023/09/A-Full-Aperture-Frequency-Scaling-Algorithm-for-Processing-Dechirped-Sliding-Spotlight-SAR-Data.pdf}, doi = {10.1109/ACCESS.2023.3308906}, year = {2023}, date = {2023-08-28}, journal = {IEEE Access}, volume = {11}, pages = {92550-92564}, abstract = {This paper proposes a full-aperture method for processing sliding spotlight synthetic aperture radar (SAR) data with dechirp-on-receive. The frequency scaling algorithm (FSA) efficiently processes the dechirped signals because the range cell migration correction (RCMC) process involves removing the residual video phase. However, the conventional FSA combined with the sub-aperture method is unsuitable for processing sliding mode data because the azimuth extent of the SAR image is limited by the system pulse repetition frequency. In addition, the azimuth compression performance deteriorates as the range displacement increases from the center of the SAR image. To address these problems, we developed a modified full-aperture FSA for sliding mode data processing. A complete signal model of the azimuth convoluted sliding mode data with the dechirp-on-receive is newly derived. Based on the signal model, the frequency scaling factor and azimuth-matched filter have been modified to accurately perform RCMC and azimuth compression. Point target simulations demonstrated two advantages of the proposed algorithm over the conventional sub-aperture approach; One is accurate and consistent azimuth compression performance regardless of range displacements, and the other is wide observable azimuth extent. The practicality of the proposed method is further verified through actual SAR raw data experiments. In addition, it is analyzed that the proposed algorithm is specialized in processing dechirped sliding mode data through a characteristic comparison with various traditional sliding spotlight processing methods.}, keywords = {International}, pubstate = {published}, tppubtype = {article} } This paper proposes a full-aperture method for processing sliding spotlight synthetic aperture radar (SAR) data with dechirp-on-receive. The frequency scaling algorithm (FSA) efficiently processes the dechirped signals because the range cell migration correction (RCMC) process involves removing the residual video phase. However, the conventional FSA combined with the sub-aperture method is unsuitable for processing sliding mode data because the azimuth extent of the SAR image is limited by the system pulse repetition frequency. In addition, the azimuth compression performance deteriorates as the range displacement increases from the center of the SAR image. To address these problems, we developed a modified full-aperture FSA for sliding mode data processing. A complete signal model of the azimuth convoluted sliding mode data with the dechirp-on-receive is newly derived. Based on the signal model, the frequency scaling factor and azimuth-matched filter have been modified to accurately perform RCMC and azimuth compression. Point target simulations demonstrated two advantages of the proposed algorithm over the conventional sub-aperture approach; One is accurate and consistent azimuth compression performance regardless of range displacements, and the other is wide observable azimuth extent. The practicality of the proposed method is further verified through actual SAR raw data experiments. In addition, it is analyzed that the proposed algorithm is specialized in processing dechirped sliding mode data through a characteristic comparison with various traditional sliding spotlight processing methods. |
| 320. | Young-Geun Kang; Seungwoon Park; Eunsung Kim; Kyeongrok Kim; Seong-Ook Park Multichannel Along-Track Interferometric SAR System Implementation Using FMCW Radar Journal Article IEEE Geoscience and Remote Sensing Letters, 20 , pp. 4009405, 2023. Abstract | Links | BibTeX | 태그: International @article{Kang2023, title = {Multichannel Along-Track Interferometric SAR System Implementation Using FMCW Radar}, author = {Young-Geun Kang and Seungwoon Park and Eunsung Kim and Kyeongrok Kim and Seong-Ook Park}, url = {http://ma.kaist.ac.kr/wp-content/uploads/2023/09/Multichannel-Along-Track-Interferometric-SAR-System-Implementation-Using-FMCW-Radar.pdf}, doi = {10.1109/LGRS.2023.3307187}, year = {2023}, date = {2023-08-21}, journal = {IEEE Geoscience and Remote Sensing Letters}, volume = {20}, pages = {4009405}, abstract = {Along-track synthetic aperture radar interferometry (ATI) systems are used to detect a moving target and to estimate its radial velocity. A dual-channel (single-baseline) ATI system estimates the velocity ambiguously because there are many candidate velocities corresponding to the interferometric phase. To resolve the ambiguity of the estimates, a multichannel (multibaseline) ATI system is required. This letter proposes an efficient implementation technique of a multichannel ATI system by using a frequency-modulated continuous wave (FMCW) radar and an antenna arrangement method considering the inherent bi-static characteristic of FMCW radars. Also, a simple and robust radial velocity estimation algorithm suitable for the proposed system model is presented. The validity of the algorithm is confirmed with simulated ATI results.}, keywords = {International}, pubstate = {published}, tppubtype = {article} } Along-track synthetic aperture radar interferometry (ATI) systems are used to detect a moving target and to estimate its radial velocity. A dual-channel (single-baseline) ATI system estimates the velocity ambiguously because there are many candidate velocities corresponding to the interferometric phase. To resolve the ambiguity of the estimates, a multichannel (multibaseline) ATI system is required. This letter proposes an efficient implementation technique of a multichannel ATI system by using a frequency-modulated continuous wave (FMCW) radar and an antenna arrangement method considering the inherent bi-static characteristic of FMCW radars. Also, a simple and robust radial velocity estimation algorithm suitable for the proposed system model is presented. The validity of the algorithm is confirmed with simulated ATI results. |
| 319. | Fathul Muin; Tommi Hariyadi; Seong-Ook Park Design and Evaluation of mmWave Backscatter Tag System for Internet of Things Applications Conference XXXVth URSI General Assembly and Scientific Symposium (URSI GASS 2023), 2023. BibTeX | 태그: International @conference{Muin2023, title = {Design and Evaluation of mmWave Backscatter Tag System for Internet of Things Applications}, author = {Fathul Muin and Tommi Hariyadi and Seong-Ook Park}, year = {2023}, date = {2023-08-19}, booktitle = {XXXVth URSI General Assembly and Scientific Symposium (URSI GASS 2023)}, keywords = {International}, pubstate = {published}, tppubtype = {conference} } |
| 318. | Ye-Eun Chi; Jinki Park; Seong-Ook Park Beamforming Transmitter for Millimeter-wave Band using Phase Detector System Conference XXXVth URSI General Assembly and Scientific Symposium (URSI GASS 2023), 2023. BibTeX | 태그: International @conference{Chi2023b, title = {Beamforming Transmitter for Millimeter-wave Band using Phase Detector System}, author = {Ye-Eun Chi and Jinki Park and Seong-Ook Park}, year = {2023}, date = {2023-08-19}, booktitle = {XXXVth URSI General Assembly and Scientific Symposium (URSI GASS 2023)}, journal = {XXXVth URSI General Assembly and Scientific Symposium (URSI GASS 2023)}, keywords = {International}, pubstate = {published}, tppubtype = {conference} } |
| 317. | Jinki Park; Ye-Eun Chi; Seong-Ook Park Liquid Crystal-Based Linear Array Element Control for Tunable Polarization RLSA Antenna Design Conference XXXVth URSI General Assembly and Scientific Symposium (URSI GASS 2023), 2023. BibTeX | 태그: International @conference{Park2023b, title = {Liquid Crystal-Based Linear Array Element Control for Tunable Polarization RLSA Antenna Design}, author = {Jinki Park and Ye-Eun Chi and Seong-Ook Park}, year = {2023}, date = {2023-08-19}, booktitle = {XXXVth URSI General Assembly and Scientific Symposium (URSI GASS 2023)}, keywords = {International}, pubstate = {published}, tppubtype = {conference} } |
| 316. | Kim Hansol; Dong-Sik Ko; Ju-hye Kim; Seong-Ook Park FMCW Proximity sensor that minimizes the influence of leakage signal Conference XXXVth URSI General Assembly and Scientific Symposium (URSI GASS 2023), 2023. BibTeX | 태그: International @conference{Hansol2023, title = {FMCW Proximity sensor that minimizes the influence of leakage signal}, author = {Kim Hansol and Dong-Sik Ko and Ju-hye Kim and Seong-Ook Park}, year = {2023}, date = {2023-08-19}, booktitle = {XXXVth URSI General Assembly and Scientific Symposium (URSI GASS 2023)}, keywords = {International}, pubstate = {published}, tppubtype = {conference} } |
| 315. | JuHong Park; SeongOok Park Micro Doppler Extraction for classification Using X-Band Chirp pulse Radar Conference XXXVth URSI General Assembly and Scientific Symposium (URSI GASS 2023), 2023. BibTeX | 태그: International @conference{Park2023c, title = {Micro Doppler Extraction for classification Using X-Band Chirp pulse Radar}, author = {JuHong Park and SeongOok Park}, year = {2023}, date = {2023-08-19}, booktitle = {XXXVth URSI General Assembly and Scientific Symposium (URSI GASS 2023)}, keywords = {International}, pubstate = {published}, tppubtype = {conference} } |
| 314. | Kyung-Bin Bae; Eun-Seong Kim; Seong-Ook Park Linear Chirp Pulse Radar System Design and Detecting Ability Verification for Small Drone Detection Conference XXXVth URSI General Assembly and Scientific Symposium (URSI GASS 2023), 2023. BibTeX | 태그: International @conference{Bae2023, title = {Linear Chirp Pulse Radar System Design and Detecting Ability Verification for Small Drone Detection}, author = {Kyung-Bin Bae and Eun-Seong Kim and Seong-Ook Park}, year = {2023}, date = {2023-08-19}, booktitle = {XXXVth URSI General Assembly and Scientific Symposium (URSI GASS 2023)}, keywords = {International}, pubstate = {published}, tppubtype = {conference} } |
| 313. | JunSung Park; SeongOok Park Drone Classification Model Using AI Algorithm Conference XXXVth URSI General Assembly and Scientific Symposium (URSI GASS 2023), 2023. BibTeX | 태그: International @conference{Park2023d, title = {Drone Classification Model Using AI Algorithm}, author = {JunSung Park and SeongOok Park}, year = {2023}, date = {2023-08-19}, booktitle = {XXXVth URSI General Assembly and Scientific Symposium (URSI GASS 2023)}, keywords = {International}, pubstate = {published}, tppubtype = {conference} } |
| 312. | Changyu Lee; Kyungbin Bae; Ashishi Singh; Seong-Ook Park C-band NLFM Pulse Radar System Design and Predistortion Technique to detect SDR based Transponder Conference XXXVth URSI General Assembly and Scientific Symposium (URSI GASS 2023), 2023. BibTeX | 태그: International @conference{Lee2023, title = {C-band NLFM Pulse Radar System Design and Predistortion Technique to detect SDR based Transponder}, author = {Changyu Lee and Kyungbin Bae and Ashishi Singh and Seong-Ook Park}, year = {2023}, date = {2023-08-19}, booktitle = {XXXVth URSI General Assembly and Scientific Symposium (URSI GASS 2023)}, keywords = {International}, pubstate = {published}, tppubtype = {conference} } |
| 311. | Yooho Jang; SeongOok Park Drone Detection and Speed Estimation Algorithm through Singular Vector in LFM Chirp Pulse Radar Conference XXXVth URSI General Assembly and Scientific Symposium (URSI GASS 2023), 2023. BibTeX | 태그: International @conference{Jang2023, title = {Drone Detection and Speed Estimation Algorithm through Singular Vector in LFM Chirp Pulse Radar}, author = {Yooho Jang and SeongOok Park}, year = {2023}, date = {2023-08-19}, booktitle = {XXXVth URSI General Assembly and Scientific Symposium (URSI GASS 2023)}, keywords = {International}, pubstate = {published}, tppubtype = {conference} } |
| 310. | Ye-Eun Chi; Jinki Park; Seong-Ook Park Hybrid Multibeamforming Receiver with High-Precision Beam Steering for Low Earth Orbit Satellite Communication Journal Article IEEE Transactions on Antennas and Propagation, 71 (7), pp. 5695-5707, 2023. Abstract | Links | BibTeX | 태그: International @article{Chi2023, title = {Hybrid Multibeamforming Receiver with High-Precision Beam Steering for Low Earth Orbit Satellite Communication}, author = {Ye-Eun Chi and Jinki Park and Seong-Ook Park}, url = {http://ma.kaist.ac.kr/wp-content/uploads/2023/09/Hybrid-Multibeamforming-Receiver-With-High-Precision-Beam-Steering-for-Low-Earth-Orbit-Satellite-Communication.pdf}, doi = {10.1109/TAP.2023.3277195}, year = {2023}, date = {2023-05-22}, journal = {IEEE Transactions on Antennas and Propagation}, volume = {71}, number = {7}, pages = {5695-5707}, abstract = {A hybrid multibeamforming receiver for low Earth orbit (LEO) satellite communication in the Ku-band is designed and tested. The proposed receiver is implemented with eight channels to enable the multibeam control. The proposed receiver, including both analog and digital beamforming structures, is capable of multibeam reception using both analog and digital beamforming techniques simultaneously or selectively. Analog beamforming is implemented by employing a local oscillator phase shifter using direct digital synthesis and phase-locked loop (PLL) structures. In digital beamforming, a software-defined radio can control the phase of the signal in the digital baseband. The multibeam received using the proposed hybrid multibeamforming receiver was measured at 11.7 and 12.7 GHz in an anechoic chamber. The phase-control resolutions of analog and digital beamforming were 0.022° and 0.72°, respectively. Analog beam-switching speed is slower than digital beamforming because it depends on the settling time of the PLL circuit, but it has a high phase-control resolution. Therefore, by using analog and digital beamforming when precise beam tilting and fast beam switching are required, respectively, the proposed hybrid multibeamforming is shown to be suitable in accordance with the communication situation.}, keywords = {International}, pubstate = {published}, tppubtype = {article} } A hybrid multibeamforming receiver for low Earth orbit (LEO) satellite communication in the Ku-band is designed and tested. The proposed receiver is implemented with eight channels to enable the multibeam control. The proposed receiver, including both analog and digital beamforming structures, is capable of multibeam reception using both analog and digital beamforming techniques simultaneously or selectively. Analog beamforming is implemented by employing a local oscillator phase shifter using direct digital synthesis and phase-locked loop (PLL) structures. In digital beamforming, a software-defined radio can control the phase of the signal in the digital baseband. The multibeam received using the proposed hybrid multibeamforming receiver was measured at 11.7 and 12.7 GHz in an anechoic chamber. The phase-control resolutions of analog and digital beamforming were 0.022° and 0.72°, respectively. Analog beam-switching speed is slower than digital beamforming because it depends on the settling time of the PLL circuit, but it has a high phase-control resolution. Therefore, by using analog and digital beamforming when precise beam tilting and fast beam switching are required, respectively, the proposed hybrid multibeamforming is shown to be suitable in accordance with the communication situation. |
| 309. | Jun Sung Park; Chul Ki Kim; Seong Ook Park A Stretched Deramping Radar Technique for High-Resolution SAR Processing in Ka-Band Using the Extended Integration Time Journal Article IEEE Transactions on Instrumentation and Measurement, 72 , 2023. Abstract | Links | BibTeX | 태그: International @article{Park2023, title = {A Stretched Deramping Radar Technique for High-Resolution SAR Processing in Ka-Band Using the Extended Integration Time}, author = {Jun Sung Park and Chul Ki Kim and Seong Ook Park}, url = {http://ma.kaist.ac.kr/wp-content/uploads/2023/09/A-Stretched-Deramping-Radar-Technique-for-High-Resolution-SAR-Processing-in-Ka-Band-Using-the-Extended-Integration-Time.pdf}, doi = {10.1109/TIM.2023.3264048}, year = {2023}, date = {2023-04-03}, journal = {IEEE Transactions on Instrumentation and Measurement}, volume = {72}, abstract = {To increase the image quality of synthetic aperture radar (SAR) is one of the hot issues for high-performance detection/reconnaissance. With this interest in the SAR technique, it generates various techniques according to the purposed platforms (Auto-SAR, ViSAR, InSAR, and PolSAR). In this article, we introduce high-efficiency and useful techniques, which can be applied to various SAR applications for generating high-quality images in the Ka -band. We proposed the stretched deramping hardware system applicable in the Ka -band, and design the Range-Doppler algorithm which well matches the proposed radar system with the modified signal parameters. Thus, we can extend the integration time of the convolution process in slow time and it leads to the improvement of the SAR image quality. To verify the performance of our proposed technique, we process the practical experiments in conventional outdoor fields. Furthermore, the proposed method is operated on the range Doppler algorithm (RDA), which is mostly used for standard SAR.}, keywords = {International}, pubstate = {published}, tppubtype = {article} } To increase the image quality of synthetic aperture radar (SAR) is one of the hot issues for high-performance detection/reconnaissance. With this interest in the SAR technique, it generates various techniques according to the purposed platforms (Auto-SAR, ViSAR, InSAR, and PolSAR). In this article, we introduce high-efficiency and useful techniques, which can be applied to various SAR applications for generating high-quality images in the Ka -band. We proposed the stretched deramping hardware system applicable in the Ka -band, and design the Range-Doppler algorithm which well matches the proposed radar system with the modified signal parameters. Thus, we can extend the integration time of the convolution process in slow time and it leads to the improvement of the SAR image quality. To verify the performance of our proposed technique, we process the practical experiments in conventional outdoor fields. Furthermore, the proposed method is operated on the range Doppler algorithm (RDA), which is mostly used for standard SAR. |
| 308. | Myoung-Ho Chae; Seong-Ook Park; Seung-Ho Choi; Chae-Taek Choi Commercial Fixed-Wing Drone Redirection System using GNSS Deception Journal Article IEEE Transactions on Aerospace and Electronic Systems, 59 (5), pp. 5699-5713, 2023. Links | BibTeX | 태그: International @article{Chae2023, title = {Commercial Fixed-Wing Drone Redirection System using GNSS Deception}, author = {Myoung-Ho Chae and Seong-Ook Park and Seung-Ho Choi and Chae-Taek Choi}, editor = {As drones become more common today, the threat of reconnaissance or attack drones to core facilities has increased, and countermeasures against them have become essential. In this study, a drone redirection system was proposed to counter illegal intrusion of commercial fixed-wing drones. The drone redirection system was designed as a closed-loop system that automatically redirects the drone to a target position. The main novelty of this study is a proposal for a system that can automatically redirect a commercial fixed-wing drone, which has not been previously explored. We proposed two strategies for redirecting drones. Additionally, simple drone modeling with a path-following algorithm was used to easily model various drones. The drone model was then tuned using flight test data, and the results were compared. Simulations were performed on the designed drone redirection system model to verify the performance of the two proposed strategies for redirecting drones in conjunction with drone fail-detection and innovation check. The performance of the drone redirection system was assessed through flight tests of Remo-M and simulations of Micropilot's hardware-in-the-loop simulator (HWILS). Through simple drone modeling, drone flight tests, and the test results from HWILS, it was proved that the drone redirection system can be applied to various fixed-wing drones.}, url = {http://ma.kaist.ac.kr/wp-content/uploads/2023/09/Commercial-Fixed-Wing-Drone-Redirection-System-using-GNSS-Deception.pdf}, doi = {10.1109/TAES.2023.3264193}, year = {2023}, date = {2023-04-03}, journal = {IEEE Transactions on Aerospace and Electronic Systems}, volume = {59}, number = {5}, pages = {5699-5713}, keywords = {International}, pubstate = {published}, tppubtype = {article} } |
2022 |
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| 307. | Laxmikant Minz; Ye-eun Chi; Kyunghoon Kwon; Min-Seon Yun; Young-Chan Moon; Duk-Yong Kim; Seong-Ook Park Utilizing Non-Orthogonal Polarization With Polarization Reuse Technique for 4 × 4 MIMO Capacity Enhancement Journal Article IEEE Access, 10 , pp. 131952-131964, 2022. Abstract | Links | BibTeX | 태그: International @article{Minz2022b, title = {Utilizing Non-Orthogonal Polarization With Polarization Reuse Technique for 4 × 4 MIMO Capacity Enhancement}, author = {Laxmikant Minz and Ye-eun Chi and Kyunghoon Kwon and Min-Seon Yun and Young-Chan Moon and Duk-Yong Kim and Seong-Ook Park}, url = {http://ma.kaist.ac.kr/wp-content/uploads/2023/03/Utilizing_Non-Orthogonal_Polarization_With_Polarization_Reuse_Technique_for_4__4_MIMO_Capacity_Enhancement.pdf}, doi = {10.1109/ACCESS.2022.3228043}, year = {2022}, date = {2022-12-09}, journal = {IEEE Access}, volume = {10}, pages = {131952-131964}, abstract = {5G communication promises fast and large data stream which requires higher capacity of a cellular wireless network. A higher capacity could be achieved with wider bandwidth and network densification, but they are expensive approaches. Instead, upgrading the wireless network with higher-order Multiple Input Multiple Output (MIMO) antenna system with polarization diversity can inexpensively escalate the peak data rate for higher capacity. We present a 4×4 MIMO cellular network scheme utilizing polarization reuse and using 4 polarization to reform the cellular network from current state of the art of dual polarization 4×4 MIMO scheme. 4 Polarization (vertical, Horizontal, ±45° slant) is used in 2 orthogonal polarization pair form, with a beam-separation among pair, to intensify polarization diversity and maximize the MIMO network channel capacity. This beam-separated polarization reuse technique minimizes the channel correlation which maximizes the probability of four independent data streams (rank 4). The simulated result of the channel capacity with the proposed scheme achieves a 30% higher capacity compared to the baseline configuration of 3-sector 4×4 MIMO. The field trial of the presented network indicates a higher portion of rank 4, supporting four independent data streams in the rich scattering environment of a cellular network.}, keywords = {International}, pubstate = {published}, tppubtype = {article} } 5G communication promises fast and large data stream which requires higher capacity of a cellular wireless network. A higher capacity could be achieved with wider bandwidth and network densification, but they are expensive approaches. Instead, upgrading the wireless network with higher-order Multiple Input Multiple Output (MIMO) antenna system with polarization diversity can inexpensively escalate the peak data rate for higher capacity. We present a 4×4 MIMO cellular network scheme utilizing polarization reuse and using 4 polarization to reform the cellular network from current state of the art of dual polarization 4×4 MIMO scheme. 4 Polarization (vertical, Horizontal, ±45° slant) is used in 2 orthogonal polarization pair form, with a beam-separation among pair, to intensify polarization diversity and maximize the MIMO network channel capacity. This beam-separated polarization reuse technique minimizes the channel correlation which maximizes the probability of four independent data streams (rank 4). The simulated result of the channel capacity with the proposed scheme achieves a 30% higher capacity compared to the baseline configuration of 3-sector 4×4 MIMO. The field trial of the presented network indicates a higher portion of rank 4, supporting four independent data streams in the rich scattering environment of a cellular network. |
| 306. | Rao Shahid Aziz; Amit Kumar Singh; Jun-Sung Park; Seong-Ook Park; Slawomir Koziel Compact electromagnetic lens antennas using cascaded metasurfaces for gain enhancement and beam steering applications Journal Article Internatioinal Journal of RF and Microwave Computer-Aided Engieering, 32 (11), pp. e23327, 2022. Abstract | Links | BibTeX | 태그: International @article{Aziz2022, title = {Compact electromagnetic lens antennas using cascaded metasurfaces for gain enhancement and beam steering applications}, author = {Rao Shahid Aziz and Amit Kumar Singh and Jun-Sung Park and Seong-Ook Park and Slawomir Koziel}, url = {http://ma.kaist.ac.kr/wp-content/uploads/2023/03/Int-J-RF-Mic-Comp-Aid-Eng-2022-Aziz-Compact-electromagnetic-lens-antennas-using-cascaded-metasurfaces-for-gain.pdf}, doi = {10.1002/mmce.23327}, year = {2022}, date = {2022-07-27}, journal = {Internatioinal Journal of RF and Microwave Computer-Aided Engieering}, volume = {32}, number = {11}, pages = {e23327}, abstract = {Electromagnetic (EM) lens antenna designs using cascaded metasurfaces for gain enhancement and beam steering applications are proposed. Two different lens aperture designs are proposed and populated with aperiodic unit cells of size 0.2λo × 0.2λo. In lens Design 1, the unit cells of different phases are distributed in concentric circular zones, whereas in lens Design 2, the unit cells of different phases are distributed in vertical linear zones on the aperture of the EM lens. Both lenses are composed of two cascaded metasurfaces with an air gap of 0.047λo (where λo = 51.7 mm at 5.8 GHz). For gain enhancement, the metasurfaces are positioned at an optimum focal distance, f = 0.61λo above source patch antenna (f/D = 0.3). Beam steering is accomplished by phase transformation of the source antenna, which can be realized by mechanically sliding the passive metasurfaces in one direction (i.e., ±x-direction) above the source antenna. The prototype of the two proposed lenses are fabricated and tested. The measured peak boresight gain obtained from Design 1 and 2 are 14.98 and 15.12 dBi, respectively. The experimental results show −25° to +25° and −27° to +27° beam steering range for Design 1 and 2, respectively, with a little gain degradation at other angles.}, keywords = {International}, pubstate = {published}, tppubtype = {article} } Electromagnetic (EM) lens antenna designs using cascaded metasurfaces for gain enhancement and beam steering applications are proposed. Two different lens aperture designs are proposed and populated with aperiodic unit cells of size 0.2λo × 0.2λo. In lens Design 1, the unit cells of different phases are distributed in concentric circular zones, whereas in lens Design 2, the unit cells of different phases are distributed in vertical linear zones on the aperture of the EM lens. Both lenses are composed of two cascaded metasurfaces with an air gap of 0.047λo (where λo = 51.7 mm at 5.8 GHz). For gain enhancement, the metasurfaces are positioned at an optimum focal distance, f = 0.61λo above source patch antenna (f/D = 0.3). Beam steering is accomplished by phase transformation of the source antenna, which can be realized by mechanically sliding the passive metasurfaces in one direction (i.e., ±x-direction) above the source antenna. The prototype of the two proposed lenses are fabricated and tested. The measured peak boresight gain obtained from Design 1 and 2 are 14.98 and 15.12 dBi, respectively. The experimental results show −25° to +25° and −27° to +27° beam steering range for Design 1 and 2, respectively, with a little gain degradation at other angles. |
| 305. | Young-Geun Kang; Goo-Hwan Shin; Seong-Ook Park Validation of the feasibility of implementing spotlight SAR mode in the NEXTSat-2 and Ka-Band Satellite Conference The 14th Global Symposium on Millimeter-Waves & Terahertz(GSMM 2022), Korea, 2022. BibTeX | 태그: International @conference{Kang2022b, title = {Validation of the feasibility of implementing spotlight SAR mode in the NEXTSat-2 and Ka-Band Satellite}, author = {Young-Geun Kang and Goo-Hwan Shin and Seong-Ook Park}, year = {2022}, date = {2022-05-18}, booktitle = {The 14th Global Symposium on Millimeter-Waves & Terahertz(GSMM 2022)}, address = {Korea}, keywords = {International}, pubstate = {published}, tppubtype = {conference} } |
| 304. | Jun-Sung Park; Chul-Ki Kim; Seong-Ook Park A Stretched De-Ramping Radar System for High-Quality SAR Image in Ka-Band Conference The 14th Global Symposium on Millimeter-Waves & Terahertz(GSMM 2022), Korea, 2022. BibTeX | 태그: International @conference{Park2022, title = {A Stretched De-Ramping Radar System for High-Quality SAR Image in Ka-Band}, author = {Jun-Sung Park and Chul-Ki Kim and Seong-Ook Park}, year = {2022}, date = {2022-05-18}, booktitle = {The 14th Global Symposium on Millimeter-Waves & Terahertz(GSMM 2022)}, address = {Korea}, keywords = {International}, pubstate = {published}, tppubtype = {conference} } |
| 303. | Ye-Eun Chi; Jinki Park; Seong-Ook Park A Novel Phase Detection System Applicable to Calibration Techniques Conference The 14th Global Symposium on Millimeter-Waves & Terahertz(GSMM 2022), Korea, 2022. BibTeX | 태그: International @conference{Chi2022, title = {A Novel Phase Detection System Applicable to Calibration Techniques}, author = {Ye-Eun Chi and Jinki Park and Seong-Ook Park}, year = {2022}, date = {2022-05-18}, booktitle = {The 14th Global Symposium on Millimeter-Waves & Terahertz(GSMM 2022)}, address = {Korea}, keywords = {International}, pubstate = {published}, tppubtype = {conference} } |
| 302. | Young-Geun Kang; Dae-Hwan Jung; Goo-Hwan Shin; Chul-Ki Kim; Seong-Ook Park A Study on the Feasibility of Stop-and-Go Approximation in FMCW SAR Journal Article Journal of Electromagnetic Engineering and Science, 22 (3), pp. 210-217, 2022. Links | BibTeX | 태그: International @article{Kang2022d, title = {A Study on the Feasibility of Stop-and-Go Approximation in FMCW SAR}, author = {Young-Geun Kang and Dae-Hwan Jung and Goo-Hwan Shin and Chul-Ki Kim and Seong-Ook Park}, url = {http://ma.kaist.ac.kr/wp-content/uploads/2022/06/jees-2022-3-r-79.pdf}, doi = {10.26866/jees.2022.3.r.79}, year = {2022}, date = {2022-04-20}, journal = {Journal of Electromagnetic Engineering and Science}, volume = {22}, number = {3}, pages = {210-217}, keywords = {International}, pubstate = {published}, tppubtype = {article} } |
| 301. | Young-Geun Kang; Chul-Ki Kim; Seong-Ook Park Ocean Image Formation Algorithm Using Altimeter Data for Next Generation Satellite SAR Journal Article Journal of Electromagnetic Engineering and Science, 22 (2), pp. 85-94, 2022. Abstract | Links | BibTeX | 태그: International @article{Kang2022, title = {Ocean Image Formation Algorithm Using Altimeter Data for Next Generation Satellite SAR}, author = {Young-Geun Kang and Chul-Ki Kim and Seong-Ook Park}, url = {http://ma.kaist.ac.kr/wp-content/uploads/2022/05/jees-2022-2-r-64.pdf}, doi = {10.26866/jees.2022.2.r.64}, year = {2022}, date = {2022-03-31}, journal = {Journal of Electromagnetic Engineering and Science}, volume = {22}, number = {2}, pages = {85-94}, abstract = {Synthetic aperture radar (SAR) obtains two-dimensional images of the Earth’s surface. Spatial resolution is one of the most important factors in evaluating SAR performance. Therefore, high operating frequencies are preferred for obtaining high resolution images. In fact, Ku-band and Ka-band are used in the automobile SAR (Auto-SAR) and the aircraft SAR (Airborne-SAR). However, the operating frequencies of the satellite SAR (Spaceborne-SAR) are limited to the X-band because of the wide Doppler frequency band caused by the satellite’s high velocity. To overcome this frequency limitation in satellite SAR, we propose a low-complexity SAR algorithm that forms images of the ocean using satellite altimeter data with an operating frequency of the Ku-band (13.575 GHz). The algorithm requires the burst mode pulse transmission technique frequently used in SAR altimeters. To validate the proposed algorithm as being suitable for ocean image formation, point target simulation and analysis are performed, and some quantitative results are provided.}, keywords = {International}, pubstate = {published}, tppubtype = {article} } Synthetic aperture radar (SAR) obtains two-dimensional images of the Earth’s surface. Spatial resolution is one of the most important factors in evaluating SAR performance. Therefore, high operating frequencies are preferred for obtaining high resolution images. In fact, Ku-band and Ka-band are used in the automobile SAR (Auto-SAR) and the aircraft SAR (Airborne-SAR). However, the operating frequencies of the satellite SAR (Spaceborne-SAR) are limited to the X-band because of the wide Doppler frequency band caused by the satellite’s high velocity. To overcome this frequency limitation in satellite SAR, we propose a low-complexity SAR algorithm that forms images of the ocean using satellite altimeter data with an operating frequency of the Ku-band (13.575 GHz). The algorithm requires the burst mode pulse transmission technique frequently used in SAR altimeters. To validate the proposed algorithm as being suitable for ocean image formation, point target simulation and analysis are performed, and some quantitative results are provided. |
| 300. | Chul-Ki Kim; Mi-Young Park; Goo-Hwan Shin; Seong-Ook Park An Improved Technique for Single-Channel Video-SAR Based on Fractional Fourier Transform Journal Article IEEE Transactions on Aerospace and Electronic Systems, 2022. Abstract | Links | BibTeX | 태그: International @article{Kim2022, title = {An Improved Technique for Single-Channel Video-SAR Based on Fractional Fourier Transform}, author = {Chul-Ki Kim and Mi-Young Park and Goo-Hwan Shin and Seong-Ook Park}, url = {http://ma.kaist.ac.kr/wp-content/uploads/2023/10/An-Improved-Technique-for-Single-Channel-Video-SAR-Based-on-Fractional-Fourier-Transform.pdf}, doi = {10.1109/TAES.2022.3157657}, year = {2022}, date = {2022-03-08}, journal = {IEEE Transactions on Aerospace and Electronic Systems}, abstract = {In the field of Synthetic Aperture Radar (SAR), a lot of researchers have tried to study an improved application beyond the conventional 2D image. Video-SAR (ViSAR) is one of the hot-issue in the SAR application. The main purpose of ViSAR is to monitor various targets in the area of interest in time order. It can offer video images to detect not only the fixed target but also the moving target. For the signal processing of ViSAR, this paper introduces the improved performance by the Doppler shifting technique with Fractional Fourier Transform (FrFT). And also, it shows that the proposed method can separate the unexpected signal of the moving target within each frame of single-channel ViSAR. Furthermore, the overall algorithm can increase efficiency and reliability in ViSAR processing. To verify the improvement of our method, we carry out the practical experiments by an X-band chirp pulse SAR system, mounted on an airplane.}, keywords = {International}, pubstate = {published}, tppubtype = {article} } In the field of Synthetic Aperture Radar (SAR), a lot of researchers have tried to study an improved application beyond the conventional 2D image. Video-SAR (ViSAR) is one of the hot-issue in the SAR application. The main purpose of ViSAR is to monitor various targets in the area of interest in time order. It can offer video images to detect not only the fixed target but also the moving target. For the signal processing of ViSAR, this paper introduces the improved performance by the Doppler shifting technique with Fractional Fourier Transform (FrFT). And also, it shows that the proposed method can separate the unexpected signal of the moving target within each frame of single-channel ViSAR. Furthermore, the overall algorithm can increase efficiency and reliability in ViSAR processing. To verify the improvement of our method, we carry out the practical experiments by an X-band chirp pulse SAR system, mounted on an airplane. |
2021 |
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| 299. | Kyei Anim; Patrick Danuor; Seong-Ook Park; Young-Bae Jung High-Efficiency Broadband Planar Array Antenna with Suspended Microstrip Slab for X-Band SAR Onboard Small Satellites Journal Article Sensors, 22 (1), pp. 252, 2021. Abstract | Links | BibTeX | 태그: International @article{Anim2021, title = {High-Efficiency Broadband Planar Array Antenna with Suspended Microstrip Slab for X-Band SAR Onboard Small Satellites}, author = {Kyei Anim and Patrick Danuor and Seong-Ook Park and Young-Bae Jung}, url = {http://ma.kaist.ac.kr/wp-content/uploads/2022/01/High-Efficiency-Broadband-Planar-Array-Antenna-with-Suspended-Microstrip-Slab-for-X-Band-SAR-Onboard-Small-Satellites.pdf}, doi = {10.3390/s22010252}, year = {2021}, date = {2021-12-30}, journal = {Sensors}, volume = {22}, number = {1}, pages = {252}, abstract = {In this paper, a high efficiency broadband planar array antenna is developed at X-band for synthetic aperture radar (SAR) on small satellites. The antenna is based on a multi-layer element structure consisting of two dielectric substrates made of Taconic TLY-5 and three copper layers (i.e., the parasitic patch (top layer), the active patch (middle layer), and the ground plane (bottom layer)). The parasitic patch resides on the bottom surface of the upper TLY-5 substrate while the active patch is printed on the top surface of the lower substrate. A Rohacell foam material is sandwiched between the top layer and the middle layer to separate the two dielectric substrates in order to achieve high directivity, wideband, and to keep the antenna weight to a minimum as required by the SAR satellite application. To satisfy the required size of the antenna panel for the small SAR satellite, an asymmetric corporate feeding network (CFN) is designed to feed a 12 × 16 planar array antenna. However, it was determined that the first corporate feed junction at the center of the CFN, where higher amplitudes of the input signal are located, contributes significantly to the leaky wave emission, which degrades the radiation efficiency and increases the sidelobe level. Thus, a suspended microstrip slab, which is simply a wide and long microstrip line, is designed and positioned on the top layer directly above that feed junction to prevent the leaky waves from radiating. The experimental results of the antenna show good agreement with the simulated ones, achieving an impedance bandwidth of 12.4% from 9.01 to 10.20 GHz and a high gain above 28 dBi. The antenna efficiency estimated from the gain and directivity eclipses 51.34%.}, keywords = {International}, pubstate = {published}, tppubtype = {article} } In this paper, a high efficiency broadband planar array antenna is developed at X-band for synthetic aperture radar (SAR) on small satellites. The antenna is based on a multi-layer element structure consisting of two dielectric substrates made of Taconic TLY-5 and three copper layers (i.e., the parasitic patch (top layer), the active patch (middle layer), and the ground plane (bottom layer)). The parasitic patch resides on the bottom surface of the upper TLY-5 substrate while the active patch is printed on the top surface of the lower substrate. A Rohacell foam material is sandwiched between the top layer and the middle layer to separate the two dielectric substrates in order to achieve high directivity, wideband, and to keep the antenna weight to a minimum as required by the SAR satellite application. To satisfy the required size of the antenna panel for the small SAR satellite, an asymmetric corporate feeding network (CFN) is designed to feed a 12 × 16 planar array antenna. However, it was determined that the first corporate feed junction at the center of the CFN, where higher amplitudes of the input signal are located, contributes significantly to the leaky wave emission, which degrades the radiation efficiency and increases the sidelobe level. Thus, a suspended microstrip slab, which is simply a wide and long microstrip line, is designed and positioned on the top layer directly above that feed junction to prevent the leaky waves from radiating. The experimental results of the antenna show good agreement with the simulated ones, achieving an impedance bandwidth of 12.4% from 9.01 to 10.20 GHz and a high gain above 28 dBi. The antenna efficiency estimated from the gain and directivity eclipses 51.34%. |
| 298. | Young-Geun Kang; Dae-Hwan Jung; Seong-Ook Park Validity of Stop-and-Go Approximation in High-Resolution Ku-band FMCW SAR with High-Velocity Platform Conference 2021 7th Asia-Pacific Conference on Synthetic Aperture Radar (APSAR), Indonesia, 2021. BibTeX | 태그: International @conference{Kang2021b, title = {Validity of Stop-and-Go Approximation in High-Resolution Ku-band FMCW SAR with High-Velocity Platform}, author = {Young-Geun Kang and Dae-Hwan Jung and Seong-Ook Park}, year = {2021}, date = {2021-11-01}, booktitle = {2021 7th Asia-Pacific Conference on Synthetic Aperture Radar (APSAR)}, journal = {2021 7th Asia-Pacific Conference on Synthetic Aperture Radar(APSAR)}, address = {Indonesia}, keywords = {International}, pubstate = {published}, tppubtype = {conference} } |
| 297. | Dong-Chan Kim; Ye-eun Chi; Junhyeong Park; Laxmikant Minz; Seong-Ook Park High Resolution Digital Beamforming Receiver Using DDS-PLL Signal Generator for 5G Mobile Communication Journal Article IEEE Transactions on Antennas and Propagation, 2021. Abstract | Links | BibTeX | 태그: International @article{Kim2021e, title = {High Resolution Digital Beamforming Receiver Using DDS-PLL Signal Generator for 5G Mobile Communication}, author = {Dong-Chan Kim and Ye-eun Chi and Junhyeong Park and Laxmikant Minz and Seong-Ook Park}, url = {http://ma.kaist.ac.kr/wp-content/uploads/2022/01/High-Resolution-Digital-Beamforming-Receiver-Using-DDS-PLL-Signal-Generator-for-5G-Mobile-Communication.pdf}, doi = {10.1109/TAP.2021.3111334}, year = {2021}, date = {2021-09-15}, journal = {IEEE Transactions on Antennas and Propagation}, abstract = {This paper presents a signal generator and a Digital Beamforming Receiver (DBR) with high phase control resolution and high beam control resolution, respectively. The signal generator is designed based on a Direct Digital Synthesizer (DDS) and a Phase Lock Loop (PLL). In the DDS-PLL signal generator, the conventional divider in PLL is replaced with a mixer, comb generator, and a doubler to utilize high phase control resolution of DDS (14bit, 0.022°) as it is and to synchronize the DDS-PLL signal generator with the entire system. In the DBR, the output signals of the DDS-PLL signal generators are used as the second Local Oscillator (LO) signal, and the beamforming technique is implemented through the change of the phase of the second LO signals. Also, for sophisticated beamforming, all signal generator components in the DBR are synchronized for generating same and fixed frequency and phase. Finally, the DBR has the same phase control resolution as the DDS, and the phase of each chain of the DBR can be adjusted up to 0.022° (14 bit). The DBR using the DDS-PLL signal generator is designed and fabricated. The DBR consists of a 1X8 array Tapered Slot Antenna (TSA) part, a 1st and 2nd frequency conversion part, a 1X8 data acquisition and combiner part, DDS-PLL signal generator part, and a reference signal generator part. The phase control performance of the DBR was verified by measuring the phase change of the chain in the DBR according to the DDS phase change. Also, to verify the beamforming performance of the DBR with high beam control resolution, the radiation pattern of the DBR when the angle of the main lobe was 0°, 0.2°, 0.4°, 15°, and 30° was measured in the 28GHz band. At the main lobe, the gain error is within 1dB and the beam angle error is within 0.2 degrees. The simulation results are in good agreement with the measured results. A high resolution beamforming performance is achieved in the DBR using the DDS-PLL signal generator.}, keywords = {International}, pubstate = {published}, tppubtype = {article} } This paper presents a signal generator and a Digital Beamforming Receiver (DBR) with high phase control resolution and high beam control resolution, respectively. The signal generator is designed based on a Direct Digital Synthesizer (DDS) and a Phase Lock Loop (PLL). In the DDS-PLL signal generator, the conventional divider in PLL is replaced with a mixer, comb generator, and a doubler to utilize high phase control resolution of DDS (14bit, 0.022°) as it is and to synchronize the DDS-PLL signal generator with the entire system. In the DBR, the output signals of the DDS-PLL signal generators are used as the second Local Oscillator (LO) signal, and the beamforming technique is implemented through the change of the phase of the second LO signals. Also, for sophisticated beamforming, all signal generator components in the DBR are synchronized for generating same and fixed frequency and phase. Finally, the DBR has the same phase control resolution as the DDS, and the phase of each chain of the DBR can be adjusted up to 0.022° (14 bit). The DBR using the DDS-PLL signal generator is designed and fabricated. The DBR consists of a 1X8 array Tapered Slot Antenna (TSA) part, a 1st and 2nd frequency conversion part, a 1X8 data acquisition and combiner part, DDS-PLL signal generator part, and a reference signal generator part. The phase control performance of the DBR was verified by measuring the phase change of the chain in the DBR according to the DDS phase change. Also, to verify the beamforming performance of the DBR with high beam control resolution, the radiation pattern of the DBR when the angle of the main lobe was 0°, 0.2°, 0.4°, 15°, and 30° was measured in the 28GHz band. At the main lobe, the gain error is within 1dB and the beam angle error is within 0.2 degrees. The simulation results are in good agreement with the measured results. A high resolution beamforming performance is achieved in the DBR using the DDS-PLL signal generator. |
| 296. | Ashish Kumar Singh; Kyung-Bin Bae; Seong-Ook Park NLFM pulse radar for drone detection using predistortion technique Journal Article Journal of Electromagnetic Waves and Applications, 35 (3), pp. 416 - 429, 2021. Abstract | Links | BibTeX | 태그: International @article{Singh2021, title = {NLFM pulse radar for drone detection using predistortion technique}, author = {Ashish Kumar Singh and Kyung-Bin Bae and Seong-Ook Park}, url = {http://ma.kaist.ac.kr/wp-content/uploads/2021/03/NLFM-pulse-radar-for-drone-detection-using-predistortion-technique-3.pdf}, doi = {10.1080/09205071.2020.1844598}, year = {2021}, date = {2021-02-11}, journal = {Journal of Electromagnetic Waves and Applications}, volume = {35}, number = {3}, pages = {416 - 429}, abstract = {The development of radar technology for the detection of small drones is getting attention of researchers. In this work, the detection of drones using Ku-band radar system has been discussed. We have utilized the advantage of nonlinear frequency modulation (NLFM) waveform for the suppression of range sidelobes. The performance and sensitivity of a radar system can be related with the linearity of system response. Here, we have made an effort to minimize non-linearity in the radar system response by using digital predistortion method. In this method, amplitude weighting coefficients have been calculated based on the received data. We have used FPGA-based transceiver for intermediate frequency (IF) signal generation and data acquisition, along with Ku-band up-down converters. The radar system was first calibrated for desired frequency band using amplitude predistortion method. In this article, experiment results for the detection of single drone and two drones using NLFM pulse signal are presented.}, keywords = {International}, pubstate = {published}, tppubtype = {article} } The development of radar technology for the detection of small drones is getting attention of researchers. In this work, the detection of drones using Ku-band radar system has been discussed. We have utilized the advantage of nonlinear frequency modulation (NLFM) waveform for the suppression of range sidelobes. The performance and sensitivity of a radar system can be related with the linearity of system response. Here, we have made an effort to minimize non-linearity in the radar system response by using digital predistortion method. In this method, amplitude weighting coefficients have been calculated based on the received data. We have used FPGA-based transceiver for intermediate frequency (IF) signal generation and data acquisition, along with Ku-band up-down converters. The radar system was first calibrated for desired frequency band using amplitude predistortion method. In this article, experiment results for the detection of single drone and two drones using NLFM pulse signal are presented. |
| 295. | Junhyeong Park; Dae-Hwan Jung; Seong-Ook Park Strategic method of determining parameter values in frequency modulated continuous wave radar for low noise floor over middle‐long range Journal Article Microwave and Optical Technology Letters, 2021. Abstract | Links | BibTeX | 태그: International @article{Park2021b, title = {Strategic method of determining parameter values in frequency modulated continuous wave radar for low noise floor over middle‐long range}, author = {Junhyeong Park and Dae-Hwan Jung and Seong-Ook Park}, url = {http://ma.kaist.ac.kr/wp-content/uploads/2021/03/mop.32805.pdf}, doi = {10.1002/mop.32805}, year = {2021}, date = {2021-02-03}, journal = {Microwave and Optical Technology Letters}, abstract = {Heterodyne architecture has been frequently chosen to resolve the problem of dc offset in frequency modulated continuous wave (FMCW) radar. However, heterodyne FMCW radars use different local oscillators, resulting in uncorrelated phase noise (UPN) in beat signals. Therefore, the inherent leakage signal in the heterodyne FMCW radar also has UPN and raises the noise floor in the power spectrum. In this letter, we propose a strategic decision method for parameter values in the heterodyne FMCW radar to achieve a low noise floor over the middle‐long range. In addition, we experimentally discover the relation between the UPN and the processing gain for the first time. Based on this relation, we devise an exact formula for the degree of improvement achieved due to the proposed strategic decision method. Experimental results confirm the devised formula and show that the proposed method significantly reduces the noise floor over the middle‐long range.}, keywords = {International}, pubstate = {published}, tppubtype = {article} } Heterodyne architecture has been frequently chosen to resolve the problem of dc offset in frequency modulated continuous wave (FMCW) radar. However, heterodyne FMCW radars use different local oscillators, resulting in uncorrelated phase noise (UPN) in beat signals. Therefore, the inherent leakage signal in the heterodyne FMCW radar also has UPN and raises the noise floor in the power spectrum. In this letter, we propose a strategic decision method for parameter values in the heterodyne FMCW radar to achieve a low noise floor over the middle‐long range. In addition, we experimentally discover the relation between the UPN and the processing gain for the first time. Based on this relation, we devise an exact formula for the degree of improvement achieved due to the proposed strategic decision method. Experimental results confirm the devised formula and show that the proposed method significantly reduces the noise floor over the middle‐long range. |
| 294. | Junhyeong Park; Jun-Sung Park; Kyung-Bin Bae; Seong-Ook Park Advanced stationary point concentration technique for leakage mitigation and small drone detection with FMCW radar Journal Article IEEE Transactions on Microwave Theory and Techniques, 69 (3), pp. 1791 - 1804, 2021. Abstract | Links | BibTeX | 태그: International @article{Park2021, title = {Advanced stationary point concentration technique for leakage mitigation and small drone detection with FMCW radar}, author = {Junhyeong Park and Jun-Sung Park and Kyung-Bin Bae and Seong-Ook Park}, url = {http://ma.kaist.ac.kr/wp-content/uploads/2021/03/09339993-4.pdfhttp://ma.kaist.ac.kr/wp-content/uploads/2021/03/09339993-5.pdf}, doi = {10.1109/TMTT.2021.3052190}, year = {2021}, date = {2021-01-28}, journal = {IEEE Transactions on Microwave Theory and Techniques}, volume = {69}, number = {3}, pages = {1791 - 1804}, abstract = {With the increase in threats posed by small drones, the development of radars to detect such drones has become a key necessity. In earlier studies, we proposed the stationary point concentration (SPC) technique for small drone detection using frequency-modulated continuous-wave (FMCW) radar. The SPC technique is a novel approach for mitigating leakage, which is an inherent problem in FMCW radar. The SPC technique improves the signal-to-noise ratio of small drones by reducing the noise floor and provides accurate distance and velocity information of such drones. However, this technique has shortcomings in its realization. In this article, we present the drawbacks of this technique and propose an advanced SPC (A-SPC) technique. The proposed technique can overcome the drawbacks of the SPC technique while implementing the benefits of the SPC technique. The experimental results verify the proposed A-SPC technique and demonstrate its robustness and usefulness.}, keywords = {International}, pubstate = {published}, tppubtype = {article} } With the increase in threats posed by small drones, the development of radars to detect such drones has become a key necessity. In earlier studies, we proposed the stationary point concentration (SPC) technique for small drone detection using frequency-modulated continuous-wave (FMCW) radar. The SPC technique is a novel approach for mitigating leakage, which is an inherent problem in FMCW radar. The SPC technique improves the signal-to-noise ratio of small drones by reducing the noise floor and provides accurate distance and velocity information of such drones. However, this technique has shortcomings in its realization. In this article, we present the drawbacks of this technique and propose an advanced SPC (A-SPC) technique. The proposed technique can overcome the drawbacks of the SPC technique while implementing the benefits of the SPC technique. The experimental results verify the proposed A-SPC technique and demonstrate its robustness and usefulness. |
| 293. | Junhyeong Park; Seong-Ook Park Improved Drone Detection in FMCW Radar using SPC Technique Conference 2020 International Symposium on Antennas and Propagation (ISAP), Japan, 2021. BibTeX | 태그: International @conference{Park2021e, title = {Improved Drone Detection in FMCW Radar using SPC Technique}, author = {Junhyeong Park and Seong-Ook Park}, year = {2021}, date = {2021-01-25}, booktitle = {2020 International Symposium on Antennas and Propagation (ISAP)}, address = {Japan}, keywords = {International}, pubstate = {published}, tppubtype = {conference} } |
2020 |
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| 292. | Hyun-Seong Kang; Byung Kwan Kim; Jun-Sung Park; Jun-Seuk Suh; Seong-Ook Park Drone Elevation Angle Classification Based on Convolutional Neural Network With Micro-Doppler of Multipolarization Journal Article IEEE Geoscience and Remote Sensing Letters, 2020. Abstract | Links | BibTeX | 태그: International @article{Kang2020c, title = {Drone Elevation Angle Classification Based on Convolutional Neural Network With Micro-Doppler of Multipolarization}, author = {Hyun-Seong Kang and Byung Kwan Kim and Jun-Sung Park and Jun-Seuk Suh and Seong-Ook Park}, doi = {10.1109/LGRS.2020.3030113}, year = {2020}, date = {2020-11-02}, journal = {IEEE Geoscience and Remote Sensing Letters}, abstract = {Multipolarizations of micro-Doppler signature (MDS) were combined to classify the elevation angle of a drone by a convolutional neural network (CNN). We classified the drone's elevation angle based on the MDS, which depends on the elevation angle of the drone. To enhance the classification accuracy, we utilized micro-Doppler from multiple polarized radar signals. We utilized and analyzed four different polarizations for the receiver, namely, vertical/horizontal/right-handed circular polarization (RHCP)/left-handed circular polarization (LHCP), while the polarization for the transmitter was vertical. The four receivers with different polarizations were fully synchronized with Tx for accurate MDS measurement for each polarization. The radar data received from the multiple polarizations were combined for the classification algorithm based on CNN. The classification rate of the elevation angles of a drone was improved from 84.745% to 97.9% compared to a single polarization by using multiple polarizations.}, keywords = {International}, pubstate = {published}, tppubtype = {article} } Multipolarizations of micro-Doppler signature (MDS) were combined to classify the elevation angle of a drone by a convolutional neural network (CNN). We classified the drone's elevation angle based on the MDS, which depends on the elevation angle of the drone. To enhance the classification accuracy, we utilized micro-Doppler from multiple polarized radar signals. We utilized and analyzed four different polarizations for the receiver, namely, vertical/horizontal/right-handed circular polarization (RHCP)/left-handed circular polarization (LHCP), while the polarization for the transmitter was vertical. The four receivers with different polarizations were fully synchronized with Tx for accurate MDS measurement for each polarization. The radar data received from the multiple polarizations were combined for the classification algorithm based on CNN. The classification rate of the elevation angles of a drone was improved from 84.745% to 97.9% compared to a single polarization by using multiple polarizations. |
| 291. | Byung Kwan Kim; Hyun-Seong Kang; Seongwook Lee; Seong-Ook Park Improved Drone Classification Using Polarimetric Merged-Doppler Images Journal Article IEEE Geoscience and Remote Sensing Letters, 2020. Abstract | Links | BibTeX | 태그: International @article{Kim2020f, title = {Improved Drone Classification Using Polarimetric Merged-Doppler Images}, author = {Byung Kwan Kim and Hyun-Seong Kang and Seongwook Lee and Seong-Ook Park}, url = {http://ma.kaist.ac.kr/wp-content/uploads/2021/03/09158523.pdf}, doi = {10.1109/LGRS.2020.3011114}, year = {2020}, date = {2020-08-04}, journal = {IEEE Geoscience and Remote Sensing Letters}, abstract = {We propose a drone classification method for polarimetric radar, based on convolutional neural network (CNN) and image processing methods. The proposed method improves drone classification accuracy when the micro-Doppler signature is very weak by the aspect angle. To utilize received polarimetric signal, we propose a novel image structure for three-channel image classification CNN. To reduce the size of data from four different polarization while securing high classification accuracy, an image processing method and structure are introduced. The data set is prepared for a three type of drone, with a polarimetric Ku-band frequency modulated continuous wave (FMCW) radar system. Proposed method is tested and verified in an anechoic chamber environment for fast evaluation. A famous CNN structure, GoogLeNet, is used to evaluate the effect of the proposed radar preprocessing. The result showed that the proposed method improved the accuracy from 89.9% to 99.8%, compared with single polarized micro-Doppler image. We compared the result from the proposed method with conventional polarimetric radar image structure and achieved similar accuracy while having half of full polarimetric data.}, keywords = {International}, pubstate = {published}, tppubtype = {article} } We propose a drone classification method for polarimetric radar, based on convolutional neural network (CNN) and image processing methods. The proposed method improves drone classification accuracy when the micro-Doppler signature is very weak by the aspect angle. To utilize received polarimetric signal, we propose a novel image structure for three-channel image classification CNN. To reduce the size of data from four different polarization while securing high classification accuracy, an image processing method and structure are introduced. The data set is prepared for a three type of drone, with a polarimetric Ku-band frequency modulated continuous wave (FMCW) radar system. Proposed method is tested and verified in an anechoic chamber environment for fast evaluation. A famous CNN structure, GoogLeNet, is used to evaluate the effect of the proposed radar preprocessing. The result showed that the proposed method improved the accuracy from 89.9% to 99.8%, compared with single polarized micro-Doppler image. We compared the result from the proposed method with conventional polarimetric radar image structure and achieved similar accuracy while having half of full polarimetric data. |
| 290. | Hyunseong Kang; Kyung-Bin Bae; Myung-Hun Jeong; Seong-Ook Park Measurement and Analysis of Radiation Leakage From a GPS Module for the Detection of Drones Journal Article IEEE Antennas and Wireless Propagation Letters, 19 (9), pp. 1610 - 1614, 2020. Abstract | Links | BibTeX | 태그: International @article{Kang2020b, title = {Measurement and Analysis of Radiation Leakage From a GPS Module for the Detection of Drones}, author = {Hyunseong Kang and Kyung-Bin Bae and Myung-Hun Jeong and Seong-Ook Park}, url = {http://ma.kaist.ac.kr/wp-content/uploads/2020/09/Measurement-and-Analysis-of-Radiation-Leakage-From-a-GPS-Module-for-the-Detection-of-Drones.pdf}, doi = {10.1109/LAWP.2020.3011851}, year = {2020}, date = {2020-07-24}, journal = {IEEE Antennas and Wireless Propagation Letters}, volume = {19}, number = {9}, pages = {1610 - 1614}, abstract = {Radiation leakage of a global positioning system (GPS) module was investigated for a drone detection system by measuring the attenuation effect and long-range detection on the outside of a building. The GPS module consisting of the radio frequency components is essential to control the flight of a drone. There is an unavoidable leakage in the GPS module during operation, and the leakage signal from the GPS module was analyzed and detected with a high-sensitivity receiver. To analyze the leakage from the GPS module during operation, we obtained the whole frequencies of leakage signals and the radiation pattern of a drone with the GPS module in an anechoic chamber. From the data, we measured the leakage signals in an outdoor space. Through outdoor measurement, it was confirmed that the theoretical attenuation effect was consistent with the measured value with a distance variation. Finally, the GPS leakage in the drone was measured up to 950 m with a high signal-to-noise ratio (SNR) of 25 dB.}, keywords = {International}, pubstate = {published}, tppubtype = {article} } Radiation leakage of a global positioning system (GPS) module was investigated for a drone detection system by measuring the attenuation effect and long-range detection on the outside of a building. The GPS module consisting of the radio frequency components is essential to control the flight of a drone. There is an unavoidable leakage in the GPS module during operation, and the leakage signal from the GPS module was analyzed and detected with a high-sensitivity receiver. To analyze the leakage from the GPS module during operation, we obtained the whole frequencies of leakage signals and the radiation pattern of a drone with the GPS module in an anechoic chamber. From the data, we measured the leakage signals in an outdoor space. Through outdoor measurement, it was confirmed that the theoretical attenuation effect was consistent with the measured value with a distance variation. Finally, the GPS leakage in the drone was measured up to 950 m with a high signal-to-noise ratio (SNR) of 25 dB. |
| 289. | Dae-Hwan Jung; Do-Hoon Kim; Muhammad Tayyab Azim; Junhyeong Park; Seong-Ook Park A Novel Signal Processing Technique for Ku-Band Automobile FMCW Fully Polarimetric SAR System Using Triangular LFM Journal Article IEEE Transactions on Instrumentation and Measurement, 2020. Abstract | Links | BibTeX | 태그: International @article{Jung2020, title = {A Novel Signal Processing Technique for Ku-Band Automobile FMCW Fully Polarimetric SAR System Using Triangular LFM}, author = {Dae-Hwan Jung and Do-Hoon Kim and Muhammad Tayyab Azim and Junhyeong Park and Seong-Ook Park}, url = {http://ma.kaist.ac.kr/wp-content/uploads/2021/03/09146876-2.pdf}, doi = {https://doi.org/10.1109/TIM.2020.3011601}, year = {2020}, date = {2020-07-24}, journal = {IEEE Transactions on Instrumentation and Measurement}, abstract = {This article presents a novel signal technique for Ku-band automobile frequency-modulated continuous-wave fully polarimetric synthetic aperture radar (FMCW PolSAR) system using triangular linear frequency modulation (LFM). Our proposed system shows the first utilizations of triangular LFM for an FMCW PolSAR. The proposed signal processing algorithm is based on the range Doppler algorithm (RDA). We developed an FMCW PolSAR system that transmits triangular LFM signals, which are used less frequently than sawtooth LFM in an SAR sensor. Using a theoretical background, we describe its configuration and how it works. We propose the novel processing solution, which forms two kinds of single-polarization images from a raw data set and is suitable for our system. We obtained all four kinds of single-polarization images from two raw data sets while using the triangular LFM. In comparison, when using sawtooth LFM, we obtained the four images from four raw data sets by repeating the RDA four times. The proposed method simplifies the FMCW PolSAR system configuration and the processing algorithm. We collected FMCW PolSAR raw data from an experimentally equipped automobile while maintaining a constant speed on a highway. The proposed algorithm and system were validated by processing a high-resolution FMCW PolSAR image.}, keywords = {International}, pubstate = {published}, tppubtype = {article} } This article presents a novel signal technique for Ku-band automobile frequency-modulated continuous-wave fully polarimetric synthetic aperture radar (FMCW PolSAR) system using triangular linear frequency modulation (LFM). Our proposed system shows the first utilizations of triangular LFM for an FMCW PolSAR. The proposed signal processing algorithm is based on the range Doppler algorithm (RDA). We developed an FMCW PolSAR system that transmits triangular LFM signals, which are used less frequently than sawtooth LFM in an SAR sensor. Using a theoretical background, we describe its configuration and how it works. We propose the novel processing solution, which forms two kinds of single-polarization images from a raw data set and is suitable for our system. We obtained all four kinds of single-polarization images from two raw data sets while using the triangular LFM. In comparison, when using sawtooth LFM, we obtained the four images from four raw data sets by repeating the RDA four times. The proposed method simplifies the FMCW PolSAR system configuration and the processing algorithm. We collected FMCW PolSAR raw data from an experimentally equipped automobile while maintaining a constant speed on a highway. The proposed algorithm and system were validated by processing a high-resolution FMCW PolSAR image. |
| 288. | Chul-Ki Kim; Muhammad Tayyab Azim; Ashish Kumar Singh; Seong-Ook Park Doppler Shifting Technique for Generating Multi-Frames of Video SAR via Sub-Aperture Signal Processing Journal Article IEEE Transactions on Signal Processing, 68 , pp. 3990 - 4001, 2020. Abstract | Links | BibTeX | 태그: International @article{Kim2020e, title = {Doppler Shifting Technique for Generating Multi-Frames of Video SAR via Sub-Aperture Signal Processing}, author = {Chul-Ki Kim and Muhammad Tayyab Azim and Ashish Kumar Singh and Seong-Ook Park}, url = {http://ma.kaist.ac.kr/wp-content/uploads/2020/09/Doppler-Shifting-Technique-for-Generating-Multi-Frames-of-Video-SAR-via-Sub-Aperture-Signal-Processing.pdf}, doi = {10.1109/TSP.2020.3006749}, year = {2020}, date = {2020-07-02}, journal = {IEEE Transactions on Signal Processing}, volume = {68}, pages = {3990 - 4001}, abstract = {The signal processing technologies of synthetic aperture radar (SAR) have been vastly studied as diverse measurement modes for various applications. One of the technologies is Video-SAR (ViSAR). It is a land-imaging mode where a sequence of images is continuously formed on the spotlight mode. We propose a new signal processing method to generate the multi-frames of ViSAR using Doppler shifting technique via sub-aperture processing. The method is based on our designed wide-angle antenna, which is a corrugated horn shape with low side lobe and Gaussian beam pattern. This wide-angle antenna receives a wide Doppler band along the azimuth direction. Based on the characteristics of the antenna, we separate the wide Doppler band into each chirp pulse signal. Each of these separated signals has a different center time. Through each chirp pulse signal in Doppler domain, the proposed method generates each frame of video at a high frame rate. The proposed ViSAR processing can show high efficiency with low computation and without a fixed coordinate system. Moreover, it can also visualize a wider area on stripmap mode than the conventional ViSAR mode, and can derive the video results based on Range Doppler Algorithm (RDA). These advantages can lead to reduce economic costs and simplify the operating ViSAR system. We have performed the practical experiments using X-band chirp pulse SAR system mounted on an airplane to verify the proposed method.}, keywords = {International}, pubstate = {published}, tppubtype = {article} } The signal processing technologies of synthetic aperture radar (SAR) have been vastly studied as diverse measurement modes for various applications. One of the technologies is Video-SAR (ViSAR). It is a land-imaging mode where a sequence of images is continuously formed on the spotlight mode. We propose a new signal processing method to generate the multi-frames of ViSAR using Doppler shifting technique via sub-aperture processing. The method is based on our designed wide-angle antenna, which is a corrugated horn shape with low side lobe and Gaussian beam pattern. This wide-angle antenna receives a wide Doppler band along the azimuth direction. Based on the characteristics of the antenna, we separate the wide Doppler band into each chirp pulse signal. Each of these separated signals has a different center time. Through each chirp pulse signal in Doppler domain, the proposed method generates each frame of video at a high frame rate. The proposed ViSAR processing can show high efficiency with low computation and without a fixed coordinate system. Moreover, it can also visualize a wider area on stripmap mode than the conventional ViSAR mode, and can derive the video results based on Range Doppler Algorithm (RDA). These advantages can lead to reduce economic costs and simplify the operating ViSAR system. We have performed the practical experiments using X-band chirp pulse SAR system mounted on an airplane to verify the proposed method. |
| 287. | Laxmikant Minz; Hyunseong Kang; Seong-Ook Park Low Reflection Coefficient Ku-Band Antenna Array for FMCW Radar Application Journal Article Progress In Electromagnetics Research, 102 , pp. 127-137, 2020. Abstract | Links | BibTeX | 태그: International @article{Minz2020b, title = {Low Reflection Coefficient Ku-Band Antenna Array for FMCW Radar Application}, author = {Laxmikant Minz and Hyunseong Kang and Seong-Ook Park}, url = {http://ma.kaist.ac.kr/wp-content/uploads/2021/03/09.20020302.pdf}, doi = {10.2528/PIERC20020302}, year = {2020}, date = {2020-05-25}, journal = {Progress In Electromagnetics Research}, volume = {102}, pages = {127-137}, abstract = {A radar for decisive target detection and tracking requires wideband, high return loss and high efficiency antenna array. In this paper, a 16 element staked-patch microstrip antenna array is presented at Ku-band with very low reflection coefficient for radar system. An aperture coupled feeding approach for a stack patch antenna is employed for wide bandwidth. A thin and low-loss tangent material, Taconic TLY-5, is used in the design of an antenna array to minimize the surface current loss and dielectric loss. Moreover, the antenna is designed with good impedance match, -30 dB, for high efficiency, by optimizing the stacked patches and utilizing reactive loading from u-slit on patch. For a low reflection coefficient antenna array over a wide bandwidth, an adequate feeding network consists of a compact and meandering stripline with metal-post around it is developed. The stripline configuration with metal-post minimizes crosstalk and lateral leakage. The feeding network developed has low reflection coefficient of -30 dB for the target band. The simulated feeding network loss is also low, 0.5 dB. The overall size of the 16 element array is compact, 295 mm x 30 mm (14λ x 1.425λ). The antenna array performance gives a reflection coefficient of -30 dB in the range of 14-14.5 GHz and total efficiency of 80%. The gain of the array is 21.54 dBi at 14.25 GHz.}, keywords = {International}, pubstate = {published}, tppubtype = {article} } A radar for decisive target detection and tracking requires wideband, high return loss and high efficiency antenna array. In this paper, a 16 element staked-patch microstrip antenna array is presented at Ku-band with very low reflection coefficient for radar system. An aperture coupled feeding approach for a stack patch antenna is employed for wide bandwidth. A thin and low-loss tangent material, Taconic TLY-5, is used in the design of an antenna array to minimize the surface current loss and dielectric loss. Moreover, the antenna is designed with good impedance match, -30 dB, for high efficiency, by optimizing the stacked patches and utilizing reactive loading from u-slit on patch. For a low reflection coefficient antenna array over a wide bandwidth, an adequate feeding network consists of a compact and meandering stripline with metal-post around it is developed. The stripline configuration with metal-post minimizes crosstalk and lateral leakage. The feeding network developed has low reflection coefficient of -30 dB for the target band. The simulated feeding network loss is also low, 0.5 dB. The overall size of the 16 element array is compact, 295 mm x 30 mm (14λ x 1.425λ). The antenna array performance gives a reflection coefficient of -30 dB in the range of 14-14.5 GHz and total efficiency of 80%. The gain of the array is 21.54 dBi at 14.25 GHz. |
| 286. | Laxmikant Minz; Seong-Ook Park Beam scanning annular slot‐ring antenna array with via‐fence for wireless power transfer Journal Article International Journal of RF and Microwave Computer-Aided Engineering, 30 (6), 2020. Abstract | Links | BibTeX | 태그: International @article{Minz2020, title = {Beam scanning annular slot‐ring antenna array with via‐fence for wireless power transfer}, author = {Laxmikant Minz and Seong-Ook Park}, url = {http://ma.kaist.ac.kr/wp-content/uploads/2020/09/Beam-scanning-annular-slot‐ring-antenna-array-with-via‐fence-for-wireless-power-transfer.pdf}, doi = {doi.org/10.1002/mmce.22178}, year = {2020}, date = {2020-02-17}, journal = {International Journal of RF and Microwave Computer-Aided Engineering}, volume = {30}, number = {6}, abstract = {Wireless power transfer has been the field of research for many decades, and with technological advancement and increase in wireless mobile devices, the future of wireless power transfer technology is very promising. The major requirement of wireless power transfer is an efficient and compact antenna array with high gain and flawless scanning performance. In this article, a 4 × 8 element array is proposed with a gain of 18 dB and scanning capability of ±45° in azimuth and elevation plane at 5.8 GHz. The overall size of the array is 100 mm × 200 mm. The element separation in the array is only 0.48 λ. There was strong mutual coupling due to smaller separation, which has been minimized with the application of via‐fence around the antenna element. A dual feed circularly polarized annular slot‐ring antenna is proposed and analyzed with via‐fence to develop an array of 4 × 8 elements. The antenna array reflection coefficient obtained is less than 20 dB for different scan angles and the gain of the array obtained is also within 2 dB for ±45° scan angles.}, keywords = {International}, pubstate = {published}, tppubtype = {article} } Wireless power transfer has been the field of research for many decades, and with technological advancement and increase in wireless mobile devices, the future of wireless power transfer technology is very promising. The major requirement of wireless power transfer is an efficient and compact antenna array with high gain and flawless scanning performance. In this article, a 4 × 8 element array is proposed with a gain of 18 dB and scanning capability of ±45° in azimuth and elevation plane at 5.8 GHz. The overall size of the array is 100 mm × 200 mm. The element separation in the array is only 0.48 λ. There was strong mutual coupling due to smaller separation, which has been minimized with the application of via‐fence around the antenna element. A dual feed circularly polarized annular slot‐ring antenna is proposed and analyzed with via‐fence to develop an array of 4 × 8 elements. The antenna array reflection coefficient obtained is less than 20 dB for different scan angles and the gain of the array obtained is also within 2 dB for ±45° scan angles. |
| 285. | Chul-Ki Kim; Laxmikant Minz; Seong-Ook Park Improved Measurement Method of Material Properties Using Continuous Cavity Perturbation Without Relocation Journal Article IEEE Transactions on Instrumentation and Measurement, 69 (8), pp. 5702 - 5716, 2020. Abstract | Links | BibTeX | 태그: International @article{Kim2020d, title = {Improved Measurement Method of Material Properties Using Continuous Cavity Perturbation Without Relocation}, author = {Chul-Ki Kim and Laxmikant Minz and Seong-Ook Park}, url = {http://ma.kaist.ac.kr/wp-content/uploads/2020/09/Improved-Measurement-Method-of-Material-Properties-Using-Continuous-Cavity-Perturbation-Without-Relocation.pdf}, doi = {10.1109/TIM.2020.2966358}, year = {2020}, date = {2020-01-14}, journal = {IEEE Transactions on Instrumentation and Measurement}, volume = {69}, number = {8}, pages = {5702 - 5716}, abstract = {Depolarized fields inside a magnetodielectric sample interfere with the accurate measurement of sample characteristics in a cavity perturbation method. These depolarized fields occur due to the polarization of the test sample, depending on the volume and shape of the sample, in the electromagnetic field. To characterize the magnetodielectric sample more accurately, we proposed an advanced rectangular cavity (RC) perturbation method. In this method, we investigated the change in the resonant frequency and Q-factor of a cavity which depends on the volume, and shape of the sample, and depolarized fields within the sample. The depolarizing factor for calculating the permittivity and permeability of the sample is derived by separating the uniform and depolarized fields within the sample when the sample is inserted in the cavity. These separations of fields play an important role to improve the measurement accuracy. The proposed unified RC perturbation technique is validated initially by measuring the resonant frequency and quality factor and then calculating the complex permittivity and permeability at the TE 10l mode. The standard dielectric material (Al 2 O 3 ) and magnetic material (YIG) samples are measured with the vector network analyzer. The measurement was performed when the magnetodielectric sample having various shapes and volumes inserted into the RC resonator. In comparison with the previous cavity perturbation methods, the permittivity and permeability have been calculated more accurately with various shapes of the test sample, and we also found that the ratio of the maximum sample volume to the cavity for various samples increases about 40%. Based on the proposed method, for a cube-shaped sample, we obtained the complex permittivity and permeability consecutively at each resonance mode without any physical relocation of the test sample. Therefore, the test sample is capable of continuous more accurate and more effective measurement in the desired frequency band without relocation using the proposed technique.}, keywords = {International}, pubstate = {published}, tppubtype = {article} } Depolarized fields inside a magnetodielectric sample interfere with the accurate measurement of sample characteristics in a cavity perturbation method. These depolarized fields occur due to the polarization of the test sample, depending on the volume and shape of the sample, in the electromagnetic field. To characterize the magnetodielectric sample more accurately, we proposed an advanced rectangular cavity (RC) perturbation method. In this method, we investigated the change in the resonant frequency and Q-factor of a cavity which depends on the volume, and shape of the sample, and depolarized fields within the sample. The depolarizing factor for calculating the permittivity and permeability of the sample is derived by separating the uniform and depolarized fields within the sample when the sample is inserted in the cavity. These separations of fields play an important role to improve the measurement accuracy. The proposed unified RC perturbation technique is validated initially by measuring the resonant frequency and quality factor and then calculating the complex permittivity and permeability at the TE 10l mode. The standard dielectric material (Al 2 O 3 ) and magnetic material (YIG) samples are measured with the vector network analyzer. The measurement was performed when the magnetodielectric sample having various shapes and volumes inserted into the RC resonator. In comparison with the previous cavity perturbation methods, the permittivity and permeability have been calculated more accurately with various shapes of the test sample, and we also found that the ratio of the maximum sample volume to the cavity for various samples increases about 40%. Based on the proposed method, for a cube-shaped sample, we obtained the complex permittivity and permeability consecutively at each resonance mode without any physical relocation of the test sample. Therefore, the test sample is capable of continuous more accurate and more effective measurement in the desired frequency band without relocation using the proposed technique. |
| 284. | Junhyeong Park; Dae-Hwan Jung; Kyung-Bin Bae; Seong-Ook Park Range-Doppler Map Improvement in FMCW Radar for Small Moving Drone Detection Using the Stationary Point Concentration Technique Journal Article IEEE Transactions on Microwave Theory and Techniques, 68 (5), pp. 1858 - 1871, 2020. Abstract | Links | BibTeX | 태그: International @article{Park2020c, title = {Range-Doppler Map Improvement in FMCW Radar for Small Moving Drone Detection Using the Stationary Point Concentration Technique}, author = {Junhyeong Park and Dae-Hwan Jung and Kyung-Bin Bae and Seong-Ook Park}, url = {http://ma.kaist.ac.kr/wp-content/uploads/2020/09/Range-Doppler-Map-Improvement-in-FMCW-Radar-for-Small-Moving-Drone-Detection-Using-the-Stationary-Point-Concentration-Technique.pdf}, doi = {10.1109/TMTT.2019.2961911}, year = {2020}, date = {2020-01-13}, journal = {IEEE Transactions on Microwave Theory and Techniques}, volume = {68}, number = {5}, pages = {1858 - 1871}, abstract = {Given the rapidly growing drone market, the development of drone detection radars has become highly important to prevent drones from damaging lives and property. Frequency-modulated continuous-wave (FMCW) radars have been frequently used for drone detection. Among the architectures of FMCW radar, a heterodyne architecture that involves different local oscillators and produces beat signals at the IF stage has often been chosen. The FMCW radar, however, has a chronic problem called leakage. In an earlier study, we proposed the stationary point concentration (SPC) technique to improve the signal-to-noise ratio (SNR) of small drones by reducing the increase in noise floor caused by leakage. We demonstrated that the proposed technique increases the SNR of small hovering drones in the 1-D power spectrum. In this article, we newly analyze the practical problems in the heterodyne FMCW radar system. One is the 2-D noise floor increase in the range-Doppler (r-D) map due to the leakage, and the other is unwanted Doppler shifts. Then, we propose an upgraded theory and realization method of the SPC technique for the detection of the small moving drone by improving the r-D map. We prove that the proposed method not only reduces the 2-D noise floor by mitigating the leakage but also removes the unwanted Doppler shifts by the phase calibration. Consequently, we show that the proposed method increases the SNR of the small moving drone and corrects its velocity information at the same time in the r-D map.}, keywords = {International}, pubstate = {published}, tppubtype = {article} } Given the rapidly growing drone market, the development of drone detection radars has become highly important to prevent drones from damaging lives and property. Frequency-modulated continuous-wave (FMCW) radars have been frequently used for drone detection. Among the architectures of FMCW radar, a heterodyne architecture that involves different local oscillators and produces beat signals at the IF stage has often been chosen. The FMCW radar, however, has a chronic problem called leakage. In an earlier study, we proposed the stationary point concentration (SPC) technique to improve the signal-to-noise ratio (SNR) of small drones by reducing the increase in noise floor caused by leakage. We demonstrated that the proposed technique increases the SNR of small hovering drones in the 1-D power spectrum. In this article, we newly analyze the practical problems in the heterodyne FMCW radar system. One is the 2-D noise floor increase in the range-Doppler (r-D) map due to the leakage, and the other is unwanted Doppler shifts. Then, we propose an upgraded theory and realization method of the SPC technique for the detection of the small moving drone by improving the r-D map. We prove that the proposed method not only reduces the 2-D noise floor by mitigating the leakage but also removes the unwanted Doppler shifts by the phase calibration. Consequently, we show that the proposed method increases the SNR of the small moving drone and corrects its velocity information at the same time in the r-D map. |
2019 |
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| 283. | Chan-Yong Jung; Kyung-Bin Bae; Dong-Chan Kim; Seong-Ook Park Internal Calibration System Using Learning Algorithm With Gradient Descent Journal Article IEEE Geoscience and Remote Sensing Letters, 17 (9), pp. 1503 - 1507, 2019. Abstract | Links | BibTeX | 태그: International @article{Jung2019d, title = {Internal Calibration System Using Learning Algorithm With Gradient Descent}, author = {Chan-Yong Jung and Kyung-Bin Bae and Dong-Chan Kim and Seong-Ook Park}, url = {http://ma.kaist.ac.kr/wp-content/uploads/2020/09/Internal-Calibration-System-Using-Learning-Algorithm-With-Gradient-Descent.pdf}, doi = {10.1109/LGRS.2019.2950671}, year = {2019}, date = {2019-11-14}, journal = {IEEE Geoscience and Remote Sensing Letters}, volume = {17}, number = {9}, pages = {1503 - 1507}, abstract = {We present a novel approach to internal calibration of a radar system. A Ku-band radar system with internal calibration paths is designed. Thermal drift of a system is mainly caused by active components, which are a high-power amplifier (HPA) and a low-noise amplifier (LNA). We aimed to reduce the drift using a learning algorithm with a gradient-descent method. Hardware offset factors and calibration factors are introduced for the process. In the learning algorithm, a penalty term is formed based on the analysis of local minimum points. The result verifies the proposed internal calibration method. Maximum deviations of gain are 0.0477 dB for the HPA and 0.0132 dB for the LNA. In addition, the maximum deviations of phase are 0.2481° for HPA and 0.0722° for LNA, respectively.}, keywords = {International}, pubstate = {published}, tppubtype = {article} } We present a novel approach to internal calibration of a radar system. A Ku-band radar system with internal calibration paths is designed. Thermal drift of a system is mainly caused by active components, which are a high-power amplifier (HPA) and a low-noise amplifier (LNA). We aimed to reduce the drift using a learning algorithm with a gradient-descent method. Hardware offset factors and calibration factors are introduced for the process. In the learning algorithm, a penalty term is formed based on the analysis of local minimum points. The result verifies the proposed internal calibration method. Maximum deviations of gain are 0.0477 dB for the HPA and 0.0132 dB for the LNA. In addition, the maximum deviations of phase are 0.2481° for HPA and 0.0722° for LNA, respectively. |
| 282. | Muhammad Tayyab Azim; Seong-Ook Park X-band Slotted Waveguide Antenna Conference 2019 International Symposium on Antennas and Propagation (ISAP), China, 2019. BibTeX | 태그: International @conference{Azim2019c, title = {X-band Slotted Waveguide Antenna}, author = {Muhammad Tayyab Azim and Seong-Ook Park}, year = {2019}, date = {2019-10-27}, booktitle = {2019 International Symposium on Antennas and Propagation (ISAP)}, address = {China}, keywords = {International}, pubstate = {published}, tppubtype = {conference} } |
| 281. | Junhyeong Park; Kyung-Bin Bae; Dae-Hwan Jung; Seong-Ook Park Micro-Drone Detection with FMCW Radar Based on Stationary Point Concentration Technique Conference 2019 International Symposium on Antennas and Propagation (ISAP), China, 2019. BibTeX | 태그: International @conference{Park2019, title = {Micro-Drone Detection with FMCW Radar Based on Stationary Point Concentration Technique}, author = {Junhyeong Park and Kyung-Bin Bae and Dae-Hwan Jung and Seong-Ook Park}, year = {2019}, date = {2019-10-27}, booktitle = {2019 International Symposium on Antennas and Propagation (ISAP)}, journal = {International Symposium on Antenna and Propagation}, address = {China}, keywords = {International}, pubstate = {published}, tppubtype = {conference} } |
| 280. | Young-Geun Kang; Chul-Ki Kim; Seong-Ook Park A Study of Multiple Image Acquisition on Stripmap SAR for Wide Beam Antenna and High Squint Case Conference 2019 International Symposium on Antennas and Propagation (ISAP), China, 2019. BibTeX | 태그: International @conference{Kang2019b, title = {A Study of Multiple Image Acquisition on Stripmap SAR for Wide Beam Antenna and High Squint Case}, author = {Young-Geun Kang and Chul-Ki Kim and Seong-Ook Park}, year = {2019}, date = {2019-10-27}, booktitle = {2019 International Symposium on Antennas and Propagation (ISAP)}, journal = {International Symposium on Antenna and Propagation}, address = {China}, keywords = {International}, pubstate = {published}, tppubtype = {conference} } |
Publications
2025 |
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| 329. | Ground-Moving Target Indication Using Along Track SAR Interferometer Designed with Triangular Frequency-Modulated Continuous Wave Radar Journal Article IEEE Transactions on Instrumentation and Measurement, n (n), pp. 1-1, 2025, ISSN: 1557-9662. |
| 328. | Reconfigurable Multibeam Holographic Antenna Based on Liquid-Crystal Technology for Ka-Band LEO Satellite Application Journal Article IEEE Access, 13 , pp. 27141-27149, 2025, ISSN: 2169-3536. |
2024 |
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| 327. | A Novel Channel Sounding Method Based on Pulsed LFM Signal for mm-Wave Application Instrumentation Measurement and Analysis Journal Article IEEE Transactions on Instrumentation and Measurement, 74 (8501216), 2024, ISSN: 1557-9662. |
| 326. | Liquid-Crystal-Based Beam Steering Guided-Wave Metasurface Antenna at Millimeter-Wave Band Journal Article IEEE Antennas and Wireless Propagation Letters, 2024. |
| 325. | Electrical Performance Analysis and Prediction for Complex Mesh based on Model Angles Journal Article IEEE Access, 2024. |
| 324. | Miniaturized 24GHz FMCW Radar Leakage Mitigation with Synchronized Subtraction Journal Article IEEE Sensors Journal, 2024. |
| 323. | Ultralow-Voltage Frequency Tunning of Liquid Crystal-Based GHz Antenna via Nanoscratching Method Journal Article Advanced Materials Technologies, 9 (7), pp. 2301859, 2024. |
| 322. | Reinforcement Learning-Based Counter Fixed-Wing Drone System Using GNSS Deception Journal Article IEEE Access, 12 , pp. 16549 - 16558, 2024. |
2023 |
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| 321. | A Full-Aperture Frequency Scaling Algorithm for Processing Dechirped Sliding Spotlight SAR Data Journal Article IEEE Access, 11 , pp. 92550-92564, 2023. |
| 320. | Multichannel Along-Track Interferometric SAR System Implementation Using FMCW Radar Journal Article IEEE Geoscience and Remote Sensing Letters, 20 , pp. 4009405, 2023. |
| 319. | Design and Evaluation of mmWave Backscatter Tag System for Internet of Things Applications Conference XXXVth URSI General Assembly and Scientific Symposium (URSI GASS 2023), 2023. |
| 318. | Beamforming Transmitter for Millimeter-wave Band using Phase Detector System Conference XXXVth URSI General Assembly and Scientific Symposium (URSI GASS 2023), 2023. |
| 317. | Liquid Crystal-Based Linear Array Element Control for Tunable Polarization RLSA Antenna Design Conference XXXVth URSI General Assembly and Scientific Symposium (URSI GASS 2023), 2023. |
| 316. | FMCW Proximity sensor that minimizes the influence of leakage signal Conference XXXVth URSI General Assembly and Scientific Symposium (URSI GASS 2023), 2023. |
| 315. | Micro Doppler Extraction for classification Using X-Band Chirp pulse Radar Conference XXXVth URSI General Assembly and Scientific Symposium (URSI GASS 2023), 2023. |
| 314. | Linear Chirp Pulse Radar System Design and Detecting Ability Verification for Small Drone Detection Conference XXXVth URSI General Assembly and Scientific Symposium (URSI GASS 2023), 2023. |
| 313. | Drone Classification Model Using AI Algorithm Conference XXXVth URSI General Assembly and Scientific Symposium (URSI GASS 2023), 2023. |
| 312. | C-band NLFM Pulse Radar System Design and Predistortion Technique to detect SDR based Transponder Conference XXXVth URSI General Assembly and Scientific Symposium (URSI GASS 2023), 2023. |
| 311. | Drone Detection and Speed Estimation Algorithm through Singular Vector in LFM Chirp Pulse Radar Conference XXXVth URSI General Assembly and Scientific Symposium (URSI GASS 2023), 2023. |
| 310. | Hybrid Multibeamforming Receiver with High-Precision Beam Steering for Low Earth Orbit Satellite Communication Journal Article IEEE Transactions on Antennas and Propagation, 71 (7), pp. 5695-5707, 2023. |
| 309. | A Stretched Deramping Radar Technique for High-Resolution SAR Processing in Ka-Band Using the Extended Integration Time Journal Article IEEE Transactions on Instrumentation and Measurement, 72 , 2023. |
| 308. | Commercial Fixed-Wing Drone Redirection System using GNSS Deception Journal Article IEEE Transactions on Aerospace and Electronic Systems, 59 (5), pp. 5699-5713, 2023. |
2022 |
|
| 307. | Utilizing Non-Orthogonal Polarization With Polarization Reuse Technique for 4 × 4 MIMO Capacity Enhancement Journal Article IEEE Access, 10 , pp. 131952-131964, 2022. |
| 306. | Compact electromagnetic lens antennas using cascaded metasurfaces for gain enhancement and beam steering applications Journal Article Internatioinal Journal of RF and Microwave Computer-Aided Engieering, 32 (11), pp. e23327, 2022. |
| 305. | Validation of the feasibility of implementing spotlight SAR mode in the NEXTSat-2 and Ka-Band Satellite Conference The 14th Global Symposium on Millimeter-Waves & Terahertz(GSMM 2022), Korea, 2022. |
| 304. | A Stretched De-Ramping Radar System for High-Quality SAR Image in Ka-Band Conference The 14th Global Symposium on Millimeter-Waves & Terahertz(GSMM 2022), Korea, 2022. |
| 303. | A Novel Phase Detection System Applicable to Calibration Techniques Conference The 14th Global Symposium on Millimeter-Waves & Terahertz(GSMM 2022), Korea, 2022. |
| 302. | A Study on the Feasibility of Stop-and-Go Approximation in FMCW SAR Journal Article Journal of Electromagnetic Engineering and Science, 22 (3), pp. 210-217, 2022. |
| 301. | Ocean Image Formation Algorithm Using Altimeter Data for Next Generation Satellite SAR Journal Article Journal of Electromagnetic Engineering and Science, 22 (2), pp. 85-94, 2022. |
| 300. | An Improved Technique for Single-Channel Video-SAR Based on Fractional Fourier Transform Journal Article IEEE Transactions on Aerospace and Electronic Systems, 2022. |
2021 |
|
| 299. | High-Efficiency Broadband Planar Array Antenna with Suspended Microstrip Slab for X-Band SAR Onboard Small Satellites Journal Article Sensors, 22 (1), pp. 252, 2021. |
| 298. | Validity of Stop-and-Go Approximation in High-Resolution Ku-band FMCW SAR with High-Velocity Platform Conference 2021 7th Asia-Pacific Conference on Synthetic Aperture Radar (APSAR), Indonesia, 2021. |
| 297. | High Resolution Digital Beamforming Receiver Using DDS-PLL Signal Generator for 5G Mobile Communication Journal Article IEEE Transactions on Antennas and Propagation, 2021. |
| 296. | NLFM pulse radar for drone detection using predistortion technique Journal Article Journal of Electromagnetic Waves and Applications, 35 (3), pp. 416 - 429, 2021. |
| 295. | Strategic method of determining parameter values in frequency modulated continuous wave radar for low noise floor over middle‐long range Journal Article Microwave and Optical Technology Letters, 2021. |
| 294. | Advanced stationary point concentration technique for leakage mitigation and small drone detection with FMCW radar Journal Article IEEE Transactions on Microwave Theory and Techniques, 69 (3), pp. 1791 - 1804, 2021. |
| 293. | Improved Drone Detection in FMCW Radar using SPC Technique Conference 2020 International Symposium on Antennas and Propagation (ISAP), Japan, 2021. |
2020 |
|
| 292. | Drone Elevation Angle Classification Based on Convolutional Neural Network With Micro-Doppler of Multipolarization Journal Article IEEE Geoscience and Remote Sensing Letters, 2020. |
| 291. | Improved Drone Classification Using Polarimetric Merged-Doppler Images Journal Article IEEE Geoscience and Remote Sensing Letters, 2020. |
| 290. | Measurement and Analysis of Radiation Leakage From a GPS Module for the Detection of Drones Journal Article IEEE Antennas and Wireless Propagation Letters, 19 (9), pp. 1610 - 1614, 2020. |
| 289. | A Novel Signal Processing Technique for Ku-Band Automobile FMCW Fully Polarimetric SAR System Using Triangular LFM Journal Article IEEE Transactions on Instrumentation and Measurement, 2020. |
| 288. | Doppler Shifting Technique for Generating Multi-Frames of Video SAR via Sub-Aperture Signal Processing Journal Article IEEE Transactions on Signal Processing, 68 , pp. 3990 - 4001, 2020. |
| 287. | Low Reflection Coefficient Ku-Band Antenna Array for FMCW Radar Application Journal Article Progress In Electromagnetics Research, 102 , pp. 127-137, 2020. |
| 286. | Beam scanning annular slot‐ring antenna array with via‐fence for wireless power transfer Journal Article International Journal of RF and Microwave Computer-Aided Engineering, 30 (6), 2020. |
| 285. | Improved Measurement Method of Material Properties Using Continuous Cavity Perturbation Without Relocation Journal Article IEEE Transactions on Instrumentation and Measurement, 69 (8), pp. 5702 - 5716, 2020. |
| 284. | Range-Doppler Map Improvement in FMCW Radar for Small Moving Drone Detection Using the Stationary Point Concentration Technique Journal Article IEEE Transactions on Microwave Theory and Techniques, 68 (5), pp. 1858 - 1871, 2020. |
2019 |
|
| 283. | Internal Calibration System Using Learning Algorithm With Gradient Descent Journal Article IEEE Geoscience and Remote Sensing Letters, 17 (9), pp. 1503 - 1507, 2019. |
| 282. | X-band Slotted Waveguide Antenna Conference 2019 International Symposium on Antennas and Propagation (ISAP), China, 2019. |
| 281. | Micro-Drone Detection with FMCW Radar Based on Stationary Point Concentration Technique Conference 2019 International Symposium on Antennas and Propagation (ISAP), China, 2019. |
| 280. | A Study of Multiple Image Acquisition on Stripmap SAR for Wide Beam Antenna and High Squint Case Conference 2019 International Symposium on Antennas and Propagation (ISAP), China, 2019. |